Added CONTRIBUTING.rst

Author: tomasbedrich

CONTRIBUTING.rst

@@ -3,9 +3,51 @@ Contributing
 ===============================================================================
 
 
-In a nutshell:
+First time
+-------------------------------------------------------------------------------
 
-- follow `PEP8 style guide <https://www.python.org/dev/peps/pep-0008/>` with **double quotes** and
-  line length of **100 characters (or 120 if absolutely nescessary)**
-- before push, run with :code:`python3 setup.py test`, then ensure **all tests are passing** and
-  **the coverage is above 95%**
+1. clone a repository from GitHub:
+
+   .. code-block:: bash
+
+       git clone https://github.com/tomasbedrich/pycaching.git
+       cd pycaching
+
+2. setup the enviroment
+
+   .. code-block:: bash
+
+       python3 setup.py develop
+
+
+Workflow in a nutshell
+-------------------------------------------------------------------------------
+
+1. Pick an issue with `contributors friendly
+   <https://github.com/tomasbedrich/pycaching/issues?q=is:open+is:issue+label:"contributors+friendly">`_
+   label and write a comment about your choice on GitHub.
+2. Write some code and tests. Follow `PEP8 <https://www.python.org/dev/peps/pep-0008/>`_ with
+   **double quotes** and line length of **100 characters** (or 120 if absolutely nescessary).
+   Don't forget to update the docs (follow `PEP257 <https://www.python.org/dev/peps/pep-0257/>`_).
+3. Run the linter and tests:
+
+   .. code-block:: bash
+
+       python3 setup.py lint test
+
+   Make sure that:
+
+   - there are no lint errors,
+   - all tests are passing,
+   - the coverage is above 95%.
+
+4. Push your work and create a pull request.
+
+
+Other instructions
+-------------------------------------------------------------------------------
+
+- **Importing modules** is okay for modules from standard library. If you want to include
+  third-party module, please consult it on GitHub before.
+- Please use regular expressions only as a last resort. When possible, use string manipulations,
+  such as :code:`split()` and then list operations. It is more readable.