doc: Update contributing doc (#219)

Organize the links and add conventional commits requirement for PRs

Author: seebees

CONTRIBUTING.md

@@ -1,18 +1,22 @@
 # Contributing Guidelines
 
-Thank you for your interest in contributing to our project. Whether it's a bug report, new feature, correction, or additional 
-documentation, we greatly value feedback and contributions from our community.
+Thank you for your interest in contributing to our project.
+Whether it's a bug report, new feature, correction, or additional documentation,
+we greatly value feedback and contributions from our community.
 
-Please read through this document before submitting any issues or pull requests to ensure we have all the necessary 
-information to effectively respond to your bug report or contribution.
+Please read through this document before submitting any issues
+or pull requests to ensure we have all the necessary information
+to effectively respond to your bug report or contribution.
 
 
 ## Reporting Bugs/Feature Requests
 
 We welcome you to use the GitHub issue tracker to report bugs or suggest features.
 
-When filing an issue, please check [existing open](https://github.com/awslabs/aws-encryption-sdk-javascript/issues), or [recently closed](https://github.com/awslabs/aws-encryption-sdk-javascript/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aclosed%20), issues to make sure somebody else hasn't already 
-reported the issue. Please try to include as much information as you can. Details like these are incredibly useful:
+When filing an issue, please check [existing open][issues], or [recently closed][recently closed],
+issues to make sure somebody else hasn't already 
+reported the issue.
+Please try to include as much information as you can. Details like these are incredibly useful:
 
 * A reproducible test case or series of steps
 * The version of our code being used
@@ -21,18 +25,26 @@ reported the issue. Please try to include as much information as you can. Detail
 
 
 ## Contributing via Pull Requests
-Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that:
+Contributions via pull requests are much appreciated.
+Before sending us a pull request, please ensure that:
 
 1. You are working against the latest source on the *master* branch.
-2. You check existing open, and recently merged, pull requests to make sure someone else hasn't addressed the problem already.
+2. You check existing open, and recently merged,
+   pull requests to make sure someone else hasn't addressed the problem already.
 3. You open an issue to discuss any significant work - we would hate for your time to be wasted.
 
 To send us a pull request, please:
 
 1. Fork the repository.
-2. Modify the source; please focus on the specific change you are contributing. If you also reformat all the code, it will be hard for us to focus on your change.
+2. Modify the source; please focus on the specific change you are contributing.
+   If you also reformat all the code, it will be hard for us to focus on your change.
 3. Ensure local tests pass.
 4. Commit to your fork using clear commit messages.
+   Your commit tile and message and pull request title and description must adhere to
+   [conventional commits][conventional commits]. Title must begin with `feat(module): title`,
+   `fix(module): title`, `docs(module): title`, `test(module): title`, `chore(module): title`.
+   Title should be lowercase and not period at the end of it. If the commit includes
+   a breaking change, the commit message must end with a single paragraph: `BREAKING CHANGE: a description of what broke`
 5. Send us a pull request, answering any default questions in the pull request interface.
 6. Pay attention to any automated CI failures reported in the pull request, and stay involved in the conversation.
 
@@ -41,21 +53,37 @@ GitHub provides additional document on [forking a repository](https://help.githu
 
 
 ## Finding contributions to work on
-Looking at the existing issues is a great way to find something to contribute on. As our projects, by default, use the default GitHub issue labels ((enhancement/bug/duplicate/help wanted/invalid/question/wontfix), looking at any ['help wanted'](https://github.com/awslabs/aws-encryption-sdk-javascript/labels/help%20wanted) issues is a great place to start. 
+Looking at the existing issues is a great way to find something to contribute on.
+As our projects, by default, use the default GitHub issue labels ((enhancement/bug/duplicate/help wanted/invalid/question/wontfix),
+looking at any [help wanted][help wanted] issues is a great place to start. 
 
 
 ## Code of Conduct
-This project has adopted the [Amazon Open Source Code of Conduct](https://aws.github.io/code-of-conduct). 
-For more information see the [Code of Conduct FAQ](https://aws.github.io/code-of-conduct-faq) or contact 
+This project has adopted the [Amazon Open Source Code of Conduct][code of conduct]. 
+For more information see the [Code of Conduct FAQ][code of conduct faq] or contact 
 opensource-codeofconduct@amazon.com with any additional questions or comments.
 
 
 ## Security issue notifications
-If you discover a potential security issue in this project we ask that you notify AWS/Amazon Security via our [vulnerability reporting page](http://aws.amazon.com/security/vulnerability-reporting/). Please do **not** create a public github issue.
-
+If you discover a potential security issue in this project we ask that you notify AWS/Amazon Security
+via our [vulnerability reporting page][vulnerability reporting].
+Please do **not** create a public github issue.
 
 ## Licensing
 
-See the [LICENSE](https://github.com/awslabs/aws-encryption-sdk-javascript/blob/master/LICENSE) file for our project's licensing. We will ask you to confirm the licensing of your contribution.
+See the [LICENSE][license] file for our project's licensing.
+We will ask you to confirm the licensing of your contribution.
+
+We may ask you to sign a [Contributor License Agreement (CLA)][cla] for larger changes.
+
+[issues]: https://github.com/awslabs/aws-encryption-sdk-javascript/issues
+[recently closed]: https://github.com/awslabs/aws-encryption-sdk-javascript/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aclosed%20
+[help wanted]: https://github.com/awslabs/aws-encryption-sdk-javascript/labels/help%20wanted
+[pr]: https://github.com/awslabs/aws-encryption-sdk-javascript/pulls
+[license]: https://github.com/awslabs/aws-encryption-sdk-javascript/blob/master/LICENSE
+[cla]: http://en.wikipedia.org/wiki/Contributor_License_Agreement
+[vulnerability reporting]: http://aws.amazon.com/security/vulnerability-reporting/
+[code of conduct]: https://aws.github.io/code-of-conduct
+[code of conduct faq]: https://aws.github.io/code-of-conduct-faq
 
-We may ask you to sign a [Contributor License Agreement (CLA)](http://en.wikipedia.org/wiki/Contributor_License_Agreement) for larger changes.
+[conventional commits]: https://www.conventionalcommits.org/