Improve CONTRIBUTING.rst doc

CONTRIBUTING.rst

@@ -3,7 +3,7 @@ Contributing
 ============
 
 Contributions are welcome, and they are greatly appreciated! Every
-little bit helps, and credit will always be given. 
+little bit helps, and credit will always be given.
 
 You can contribute in many ways:
 
@@ -33,10 +33,19 @@ Implement Features
 Look through the GitHub issues for features. Anything tagged with "feature"
 is open to whoever wants to implement it.
 
+Branching model
+~~~~~~~~~~~~~~~
+
+When planning a code cotnribution, these is the project branching model:
+
+* new features goes to develop
+* bugfixes for releases goes to release/Y.Z.x branches
+* master is just a snapshot of the latest stable release and should not be targeted
+
 Write Documentation
 ~~~~~~~~~~~~~~~~~~~
 
-djangocms-blog could always use more documentation, whether as part of the 
+djangocms-blog could always use more documentation, whether as part of the
 official djangocms-blog docs, in docstrings, or even on the web in blog posts,
 articles, and such.
 
@@ -81,7 +90,7 @@ tests, including testing other Python versions with tox::
 	$ python setup.py test
     $ tox
 
-To get flake8 and tox, just pip install them into your virtualenv. 
+To get flake8 and tox, just pip install them into your virtualenv.
 
 6. Commit your changes and push your branch to GitHub::
 
@@ -100,7 +109,7 @@ Before you submit a pull request, check that it meets these guidelines:
 2. If the pull request adds functionality, the docs should be updated. Put
    your new functionality into a function with a docstring, and add the
    feature to the list in README.rst.
-3. The pull request should work for Python 2.6, 2.7, and 3.3, and for PyPy. Check 
+3. The pull request should work for Python 2.6, 2.7, and 3.3, and for PyPy. Check
    https://travis-ci.org/nephila/djangocms-blog/pull_requests
    and make sure that the tests pass for all supported Python versions.