Add .rst suffix to documentation files so that github auto-formats them

docs/code_style

@@ -1,18 +0,0 @@
-Basically, PEP8
-
-- Max line width: 80 chars.
-- Use camel case for class and type names
-- Use underscores for functions and variables.
-- Use double quotes.
-- Use parentheses instead of '\' for line continuation where ever possible (which is pretty much everywhere)
-- There should be max a single new line between:
-    - statements
-    - functions in a class
-- There should be two new lines between:
-    - definitions in a module (e.g., between different classes)
-- There should be spaces where spaces should be and not where there shouldn't be:
-    - a single space after a comma
-    - a single space before and after for '=' when used as assignment
-    - no spaces before and after for '=' for default values and keyword arguments.
-
-Comments should follow the google code style. This is so that we can generate documentation with sphinx (http://sphinxcontrib-napoleon.readthedocs.org/en/latest/)