Merge pull request #1732 from cryos/updates

Added some detail on the DCO

Author: cryos

CONTRIBUTING.md

@@ -6,3 +6,16 @@ integration. Please check our [building guide][BUILDING.md] and our
 [style guide][STYLE.md] for more details on developing and contributing to the
 project. The GitHub issue tracker can be used to report bugs, make feature
 requests, etc.
+
+We require that all contributions conform to the
+[Developer Certificate of Origin][dco]. In short, when making commits add the
+`-s` option to the commit command, this will add the required signed-off-by
+line which is verified by a bot when pull requests are submitted. This signifies
+your agreement to the terms of contribution outlined in the
+[Developer Certificate of Origin][dco].
+
+```
+$ git commit -s -v -m 'This is my commit message'
+```
+
+  [dco]: https://developercertificate.org/