chore(docs): update readme.md links to match Netlify's docs (#50)

* Edited netlify's docs URLs to match current ones

* updated configuration link

* Update README.md

Author: gangsthub

README.md

@@ -57,19 +57,17 @@ This module will look for the Netlify CMS config file and extensions in the foll
 
 #### Netlify CMS `config.yml`
 
-You can specify a [custom configuration](https://www.netlifycms.org/docs/#configuration), that will be parsed and merged with the module's [netlify CMS options](#cmsconfig).
+You can specify a [custom configuration](https://www.netlifycms.org/docs/add-to-your-site/#configuration), that will be parsed and merged with the module's [netlify CMS options](#cmsconfig).
 
 You have to place the file in your Netlify CMS module config folder and name it `config.yml`.
 
 :information_source: Note that each path in the file (`media_folder`, collections `folder` fields and collections `file` fields) will be rewritten to prepend nuxt.js [srcDir](https://nuxtjs.org/api/configuration-srcdir/), so please specify each path relative to this folder.
 
 This file can be changed while `nuxt dev` is running, and Netlify CMS will be updated automatically.
 
-#### Netlify CMS extensions
+#### Netlify CMS customizations
 
-This module will look for [Netlify CMS extensions](https://github.com/netlify/netlify-cms/blob/master/docs/intro.md#customization) in \*.js files contained in Netlify CMS module config folder and subfolders, and include them in the CMS build.
-
-These are of two kinds, [Custom Previews](https://www.netlifycms.org/docs/customization/) and [Widgets](https://www.netlifycms.org/docs/extending/).
+These are of two kinds, [Custom Previews](https://www.netlifycms.org/docs/customization/) and [Custom Widgets](https://www.netlifycms.org/docs/custom-widgets/).
 
 :information_source: The global variable `CMS` is available to these javascript files to reference the CMS object.