Create CONTRIBUTING.md

Author: dcwhite

.github/CONTRIBUTING.md

@@ -0,0 +1,9 @@
+TODO: Contribution guide. Follow this example:
+
+https://github.com/atom/atom/blob/master/CONTRIBUTING.md
+
+TODO add contribution guidelines. These could include:
+
+    Steps for creating good issues or pull requests.
+    Links to external documentation, mailing lists, or a code of conduct.
+    Community and behavioral expectations.