docs: jest-dom for custom Jest matchers and blog post (#100)

* Recommend jest-dom for custom Jest matchers

dom-testing-library has custom Jest matchers for convenience however for developers using Jest and react-testing-library it should be recommended to use jest-dom.

* Add me as contributor and type

* Add blog post about unit testing React JS

Author: rkotze

.all-contributorsrc

@@ -286,6 +286,15 @@
         "example",
         "ideas"
       ]
+    },
+    {
+      "login": "rkotze",
+      "name": "Richard Kotze (mobile)",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/10452163?v=4",
+      "profile": "http://www.richardkotze.com",
+      "contributions": [
+        "doc"
+      ]
     }
   ]
 }

README.md

@@ -16,7 +16,7 @@
 [![downloads][downloads-badge]][npmtrends]
 [![MIT License][license-badge]][license]
 
-[![All Contributors](https://img.shields.io/badge/all_contributors-28-orange.svg?style=flat-square)](#contributors)
+[![All Contributors](https://img.shields.io/badge/all_contributors-29-orange.svg?style=flat-square)](#contributors)
 [![PRs Welcome][prs-badge]][prs]
 [![Code of Conduct][coc-badge]][coc]
 [![Join the community on Spectrum][spectrum-badge]][spectrum]
@@ -117,17 +117,17 @@ npm install --save-dev react-testing-library
 
 This library has a `peerDependencies` listing for `react-dom`.
 
-You may also be interested in installing `dom-testing-library` so you can use
-[the custom jest matchers](https://github.com/kentcdodds/dom-testing-library/blob/master/README.md#custom-jest-matchers)
+You may also be interested in installing `jest-dom` so you can use
+[the custom jest matchers](https://github.com/gnapse/jest-dom#readme)
 
 ## Usage
 
 ```javascript
 // __tests__/fetch.js
 import React from 'react'
 import {render, Simulate, wait} from 'react-testing-library'
-// this add custom expect matchers from dom-testing-library
-import 'dom-testing-library/extend-expect'
+// this add custom jest matchers from jest-dom
+import 'jest-dom/extend-expect'
 import axiosMock from 'axios' // the mock lives in a __mocks__ directory
 import Fetch from '../fetch' // see the tests for a full implementation
 
@@ -638,6 +638,7 @@ Some included are:
 * [Testing React and Web Applications](https://kentcdodds.com/workshops/#testing-react-and-web-applications)
 * [Build a joke app with TDD](https://medium.com/@mbaranovski/quick-guide-to-tdd-in-react-81888be67c64) by [@mbaranovski](https://github.com/mbaranovski)
 * [Build a comment feed with TDD](https://medium.freecodecamp.org/how-to-build-sturdy-react-apps-with-tdd-and-the-react-testing-library-47ad3c5c8e47) by [@iwilsonq](https://github.com/iwilsonq)
+* [A clear way to unit testing React JS components using Jest and react-testing-library](https://www.richardkotze.com/coding/react-testing-library-jest) by [Richard Kotze](https://github.com/rkotze)
 
 Feel free to contribute more!
 
@@ -911,6 +912,7 @@ Thanks goes to these people ([emoji key][emojis]):
 | [<img src="https://avatars1.githubusercontent.com/u/1241511?s=460&v=4" width="100px;"/><br /><sub><b>Anto Aravinth</b></sub>](https://github.com/antoaravinth)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=antoaravinth "Code") [⚠️](https://github.com/kentcdodds/react-testing-library/commits?author=antoaravinth "Tests") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=antoaravinth "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/3462296?v=4" width="100px;"/><br /><sub><b>Jonah Moses</b></sub>](https://github.com/JonahMoses)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=JonahMoses "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/4002543?v=4" width="100px;"/><br /><sub><b>Łukasz Gandecki</b></sub>](http://team.thebrain.pro)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=lgandecki "Code") [⚠️](https://github.com/kentcdodds/react-testing-library/commits?author=lgandecki "Tests") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=lgandecki "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/498274?v=4" width="100px;"/><br /><sub><b>Ivan Babak</b></sub>](https://sompylasar.github.io)<br />[🐛](https://github.com/kentcdodds/react-testing-library/issues?q=author%3Asompylasar "Bug reports") [🤔](#ideas-sompylasar "Ideas, Planning, & Feedback") | [<img src="https://avatars3.githubusercontent.com/u/4439618?v=4" width="100px;"/><br /><sub><b>Jesse Day</b></sub>](https://github.com/jday3)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=jday3 "Code") | [<img src="https://avatars0.githubusercontent.com/u/15199?v=4" width="100px;"/><br /><sub><b>Ernesto García</b></sub>](http://gnapse.github.io)<br />[💬](#question-gnapse "Answering Questions") [💻](https://github.com/kentcdodds/react-testing-library/commits?author=gnapse "Code") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=gnapse "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/2747424?v=4" width="100px;"/><br /><sub><b>Josef Maxx Blake</b></sub>](http://jomaxx.com)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=jomaxx "Code") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=jomaxx "Documentation") [⚠️](https://github.com/kentcdodds/react-testing-library/commits?author=jomaxx "Tests") |
 | [<img src="https://avatars1.githubusercontent.com/u/29602306?v=4" width="100px;"/><br /><sub><b>Michal Baranowski</b></sub>](https://twitter.com/baranovskim)<br />[📝](#blog-mbaranovski "Blogposts") [✅](#tutorial-mbaranovski "Tutorials") | [<img src="https://avatars3.githubusercontent.com/u/13985684?v=4" width="100px;"/><br /><sub><b>Arthur Puthin</b></sub>](https://github.com/aputhin)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=aputhin "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/21194045?v=4" width="100px;"/><br /><sub><b>Thomas Chia</b></sub>](https://github.com/thchia)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=thchia "Code") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=thchia "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/20430611?v=4" width="100px;"/><br /><sub><b>Thiago Galvani</b></sub>](http://ilegra.com/)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=thiagopaiva99 "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/19828824?v=4" width="100px;"/><br /><sub><b>Christian</b></sub>](http://Chriswcs.github.io)<br />[⚠️](https://github.com/kentcdodds/react-testing-library/commits?author=ChrisWcs "Tests") | [<img src="https://avatars3.githubusercontent.com/u/1571667?v=4" width="100px;"/><br /><sub><b>Alex Krolick</b></sub>](https://alexkrolick.com)<br />[💬](#question-alexkrolick "Answering Questions") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=alexkrolick "Documentation") [💡](#example-alexkrolick "Examples") [🤔](#ideas-alexkrolick "Ideas, Planning, & Feedback") | [<img src="https://avatars3.githubusercontent.com/u/1239401?v=4" width="100px;"/><br /><sub><b>Johann Hubert Sonntagbauer</b></sub>](https://github.com/johann-sonntagbauer)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=johann-sonntagbauer "Code") [📖](https://github.com/kentcdodds/react-testing-library/commits?author=johann-sonntagbauer "Documentation") [⚠️](https://github.com/kentcdodds/react-testing-library/commits?author=johann-sonntagbauer "Tests") |
 | [<img src="https://avatars2.githubusercontent.com/u/2224291?v=4" width="100px;"/><br /><sub><b>Maddi Joyce</b></sub>](http://www.maddijoyce.com)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=maddijoyce "Code") | [<img src="https://avatars2.githubusercontent.com/u/10080111?v=4" width="100px;"/><br /><sub><b>Ryan Vice</b></sub>](http://www.vicesoftware.com)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=RyanAtViceSoftware "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/7942604?v=4" width="100px;"/><br /><sub><b>Ian Wilson</b></sub>](https://ianwilson.io)<br />[📝](#blog-iwilsonq "Blogposts") [✅](#tutorial-iwilsonq "Tutorials") | [<img src="https://avatars2.githubusercontent.com/u/1635491?v=4" width="100px;"/><br /><sub><b>Daniel</b></sub>](https://github.com/InExtremaRes)<br />[🐛](https://github.com/kentcdodds/react-testing-library/issues?q=author%3AInExtremaRes "Bug reports") [💻](https://github.com/kentcdodds/react-testing-library/commits?author=InExtremaRes "Code") | [<img src="https://avatars0.githubusercontent.com/u/767959?v=4" width="100px;"/><br /><sub><b>Giorgio Polvara</b></sub>](https://twitter.com/Gpx)<br />[🐛](https://github.com/kentcdodds/react-testing-library/issues?q=author%3AGpx "Bug reports") [🤔](#ideas-Gpx "Ideas, Planning, & Feedback") | [<img src="https://avatars2.githubusercontent.com/u/132233?v=4" width="100px;"/><br /><sub><b>John Gozde</b></sub>](https://github.com/jgoz)<br />[💻](https://github.com/kentcdodds/react-testing-library/commits?author=jgoz "Code") | [<img src="https://avatars0.githubusercontent.com/u/8203211?v=4" width="100px;"/><br /><sub><b>Sam Horton</b></sub>](https://twitter.com/SavePointSam)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=SavePointSam "Documentation") [💡](#example-SavePointSam "Examples") [🤔](#ideas-SavePointSam "Ideas, Planning, & Feedback") |
+| [<img src="https://avatars2.githubusercontent.com/u/10452163?v=4" width="100px;"/><br /><sub><b>Richard Kotze (mobile)</b></sub>](http://www.richardkotze.com)<br />[📖](https://github.com/kentcdodds/react-testing-library/commits?author=rkotze "Documentation") |
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors][all-contributors] specification.