adding the standard contribution statement

CONTRIBUTING.md

@@ -0,0 +1,26 @@
+# Contributing
+
+If you haven't already read through them, we recommend the starting with the
+[Azure contribution guidelines][azure-oss].
+
+## Legal
+You will need to complete a Contributor License Agreement (CLA). Briefly, this
+agreement testifies that you are granting us permission to use the submitted
+change according to the terms of the project's license, and that the work being
+submitted is under appropriate copyright.
+
+Please submit a [Contributor License Agreement (CLA)](https://cla.azure.com/)
+before submitting a pull request. This process is automated and should be
+painless.
+
+## Housekeeping
+Your pull request should:
+
+* Include a description of what your change intends to do.
+* Be based on a reasonably recent commit in the `master` branch.
+
+## Be nice
+We might be slower than you'd like. We might also ask you to make changes to the
+pull request. We ask for your patience. :smiley:
+
+[azure-oss]: http://azure.github.io/guidelines/