docs(contributing): update contributing guide

CONTRIBUTING.md

@@ -1,17 +1,41 @@
+Hi collaborator!
+
+We use **pull request** based approach to development.
+
+**Have a fix or a new feature**? Search for corresponding issues first then
+create a new one.
+
+If you have a new **API proposal** or change, create an issue describing it precisely:
+- JavaScript example
+- Resulting DOM/effect
+
+Once **you are ready** to start working:
+- **assign** the task to yourself
+- **create a branch** starting from the **develop** branch
+- see [development workflow](#development-workflow)
+- use our [commit message guidelines](#commit-message-guidelines) to provide a meaningful commit message (it will be inserted into the changelog automatically)
+- add a [#fix #issue](https://help.github.com/articles/closing-issues-via-commit-messages/) when relevant
+- **submit** your pull request to the develop branch
+- wait for **review**
+- do the necessary changes
+- **rebase** your pull request to avoid commits like "fix dangling comma in bro.js", "fix after review"
+
 # Development workflow
 
+Rapidly iterate with our example app:
+
 ```sh
 npm install
 npm run dev
 ```
 
-# Test and lint
+Run the tests and lint:
 
 ```sh
 npm test
 ```
 
-# Commits guidelines
+# Commit message guidelines
 
 We use [conventional changelog](https://github.com/ajoslin/conventional-changelog),
 please [follow the rules for committing](https://github.com/ajoslin/conventional-changelog/blob/master/conventions/angular.md), it helps reducing the commit noise.