Include / Link to How To Contribute wiki page

CONTRIBUTING.md

@@ -0,0 +1,22 @@
+Contributions are very welcome. The easiest way is to fork the repo and then
+make a pull request from your fork. Before your pull request is merged, it will
+be reviewed by at least one person. There may be feedback so expect comments on
+the pull request. Add yourself to the AUTHORS file in your first pull request.
+
+Please review:
+
+* [Python Guidelines](https://github.com/edx/edx-platform/wiki/Python-Guidelines)
+* [Javascript Guidelines](https://github.com/edx/edx-platform/wiki/Javascript-Guidelines)
+* [Testing](https://github.com/edx/edx-platform/blob/master/docs/internal/testing.md)
+
+Coding conventions should be followed and your commit should *increase* test
+coverage, not decrease it. For more involved contributions, you may want to
+discuss your intentions on the mailing list *before* you start coding.
+
+Before your first pull request is merged, you'll need to sign the
+[individual contributor agreement](http://code.edx.org/individual-contributor-agreement.pdf)
+and send it in. This confirms you have the authority to contribute the code in
+the pull request and ensures we can relicense it.
+
+If you have any questions, please ask on the
+[mailing list](https://groups.google.com/forum/#!forum/edx-code).

README.md

@@ -345,9 +345,9 @@ with `overview.md` to get an introduction to the architecture of the system.
 How to Contribute
 -----------------
 
-Contributions are very welcome. The easiest way is to fork this repo, and then
-make a pull request from your fork. The first time you make a pull request, you
-may be asked to sign a Contributor Agreement.
+Contributions are very welcome.
+
+Please read [How To Contribute](https://github.com/edx/edx-platform/wiki/How-To-Contribute) for details.
 
 Reporting Security Issues
 -------------------------