Clean up and complete RTD documentation

readthedocs/extra/developing/coding-style.rst

@@ -0,0 +1,22 @@
+============
+Coding Style
+============
+
+
+Basically, make it **readable**, while keeping the style similar to the
+code of whatever file you're working on.
+
+Also note that not everyone has 4K screens for their primary monitors,
+so please try to stick to the 80-columns limit. This makes it easy to
+``git diff`` changes from a terminal before committing changes. If the
+line has to be long, please don't exceed 120 characters.
+
+For the commit messages, please make them *explanatory*. Not only
+they're helpful to troubleshoot when certain issues could have been
+introduced, but they're also used to construct the change log once a new
+version is ready.
+
+If you don't know enough Python, I strongly recommend reading `Dive Into
+Python 3 <http://www.diveintopython3.net/>`__, available online for
+free. For instance, remember to do ``if x is None`` or
+``if x is not None`` instead ``if x == None``!