Update CONTRIBUTING.md.

CONTRIBUTING.md

@@ -6,18 +6,20 @@ We are happy to accept any contributions that make sense and respect the rules l
 
 1. Fork the repo.
 2. Create a feature branch for your contribution out of the `develop` branch. We use the [git-flow][gitflow-tool] tool to implement the [successful Git branching model][gitflow-post]. Only one contribution per branch is accepted.
-3. Implement your contribution while respecting our [Coding style][].
-    - Do not touch the `version` field in [package.json](package.json).
-    - Do not commit any generated files, unless already in the repo. If absolutely necessary, explain why.
+3. Implement your contribution while respecting our rules (see below).
 4. Run `npm test` to make sure you didn't break anything.
 5. Add tests for your contribution so that no one else will break it.
 6. Submit a pull request against our `develop` branch!
 
-## Coding style
+## Rules
 
-1. Attempt to conform to existing coding style so that your contribution fits in.
-2. Use [EditorConfig] to enforce our [whitespace rules](.editorconfig). If your editor is not supported, enforce the settings manually.
-3. Run `npm test` for CoffeeLint, JSONLint and unit test coverage.
+* **Do** use feature branches.
+* **Do** conform to existing coding style so that your contribution fits in.
+* **Do** use [EditorConfig] to enforce our [whitespace rules](.editorconfig). If your editor is not supported, enforce the settings manually.
+* **Do** run `npm test` for CoffeeLint, JSONLint and unit test coverage.
+* **Do not** touch the `version` field in [package.json](package.json).
+* **Do not** commit any generated files, unless already in the repo. If absolutely necessary, explain why.
+* **Do not** create any top level files or directories. If absolutely necessary, explain why and update [.npmignore](.npmignore).
 
 ## License