Adding a CONTRIBUTING file.

Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>

CONTRIBUTING.md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..4f7b47e
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1 @@
+See the [./docs/contributing.rst](./docs/contributing.rst) file.

docs/contributing.rst

diff --git a/docs/contributing.rst b/docs/contributing.rst
new file mode 100644
index 0000000..14f6b0f
--- /dev/null
+++ b/docs/contributing.rst
@@ -0,0 +1,36 @@
+How to Contribute
+=================
+
+We'd love to accept your patches and contributions to this project.
+There are just a few small guidelines you need to follow.
+
+Contributor License Agreement
+-----------------------------
+
+Contributions to this project must be accompanied by a Contributor
+License Agreement. You (or your employer) retain the copyright to your
+contribution; this simply gives us permission to use and redistribute
+your contributions as part of the project. Head over to
+https://cla.developers.google.com/ to see your current agreements on
+file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already
+submitted one (even if it was for a different project), you probably
+don't need to do it again.
+
+Code reviews
+------------
+
+All submissions, including submissions by project members, require
+review. We use GitHub pull requests for this purpose. Consult `GitHub
+Help <https://help.github.com/articles/about-pull-requests/>`__ for more
+information on using pull requests.
+
+Community Guidelines
+--------------------
+
+This project follows `Google's Open Source Community
+Guidelines <https://opensource.google/conduct/>`__.
+
+.. include:: code-of-conduct.rst
+    :start-after: community_guidelines_text