Add contribution docs to README

README.md

@@ -106,6 +106,26 @@ generator.getTemplateFile({
 
 * Node.js v7.6+
 
+## Contributing
+
+Contributions are more than welcome. If you want to make a contribution, please make sure you go through the following steps:
+
+1. Pick or create an issue. It's always a good idea to leave a message saying that you're going to work on it before you start any actual work.
+2. Open a Pull Request pointing to `develop` branch.
+3. A maintainer will review and, eventually, merge your Pull Request. Please, be patient as most of us are doing this in our spare time.
+
+If you're a maintainer, take it from here:
+
+1. Merge Pull Request into `develop`.
+2. Make sure your local `develop` and `master` branches are up to date.
+3. Switch to `develop` branch.
+4. Whenever you think it makes sense, make a release:
+  a. From develop branch, run: `git flow release start X.X.X`.
+  b. In release branch, update version in `package.json` and `package-lock.json`.
+  c. In release branch, run: `git flow release finish X.X.X`.
+  d. You should now be in `develop` branch. Run: `git push --tags && git checkout master && git push`.
+5. Release to NPM should happen automatically. You can check status at https://travis-ci.org/asyncapi/asyncapi.
+
 ## Author
 
 Fran Méndez ([@fmvilas](http://twitter.com/fmvilas))