Merge branch 'dco' into contributing-github

* dco:
  developer-certificate-of-origin: Add v1.1 from the Linux Foundation

Signed-off-by: W. Trevor King <wking@tremily.us>
CONTRIBUTING.md: Update SubmittingPatches link

And link to the newly-local DCO.

Signed-off-by: W. Trevor King <wking@tremily.us>