Contributing instructions

Towards closing #701.

CONTRIBUTING.rst

@@ -0,0 +1,45 @@
+Welcome to the Rasterio project. Here's how we work.
+
+Code of Conduct
+===============
+
+First of all: the Rasterio project has a code of conduct. Please read the
+CODE_OF_CONDUCT.txt file, it's important to all of us.
+
+Design Principles
+=================
+
+TODO
+
+Code Conventions
+================
+
+The ``rasterio`` namespace contains both Python and C extension modules. All
+C extension modules are written using `Cython <http://cython.org/>`__. The
+Cython language is a superset of Python. Cython files end with ``.pyx`` and
+``.pxd`` and are where we keep all the code that calls C functions in the GDAL
+library.
+
+Rasterio supports Python 2 and Python 3 in the same code base.
+
+We strongly prefer code adhering to `PEP8 <https://www.python.org/dev/peps/pep-0008/>`__.
+
+Tests are mandatory for new features. We use ``pytest``.
+
+We aspire to 100% coverage for Python modules. Coverage of the Cython code is
+a future aspiration.
+
+Git Conventions
+===============
+
+TODO
+
+Issue Conventions
+=================
+
+TODO
+
+Development Environment
+=======================
+
+TODO