More fully document the contribution process, move most of the details from
CONTRIBUTING.rst to sphinx.
diff --git a/docs/index.rst b/docs/index.rst
index 34996d7..c8f6388 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -32,4 +32,5 @@
 
     architecture
     primitives/index
+    contributing
     community