Add new contributing rules

docs/sanic/contributing.md

@@ -4,10 +4,39 @@ Thank you for your interest! Sanic is always looking for contributors. If you
 don't feel comfortable contributing code, adding docstrings to the source files
 is very appreciated.
 
+## Installation
+
+To develop on sanic (and mainly to just run the tests) it is highly recommend to
+install from sources.
+
+So assume you have already cloned the repo and are in the working directory with
+a virtual environment already set up, then run:
+
+```bash
+python setup.py develop && pip install -r requirements-dev.txt
+```
+
 ## Running tests
 
-* `python -m pip install pytest`
-* `python -m pytest tests`
+To run the tests for sanic it is recommended to use tox like so:
+
+```bash
+tox
+```
+
+See it's that simple!
+
+## Pull requests!
+
+So the pull request approval rules are pretty simple:
+1. All pull requests must pass unit tests
+* All pull requests must be reviewed and approved by at least 
+one current collaborator on the project
+* All pull requests must pass flake8 checks
+* If you decide to remove/change anything from any common interface
+a deprecation message should accompany it.
+* If you implement a new feature you should have at least one unit
+test to accompany it.
 
 ## Documentation