CONTRIBUTING.md: Update SubmittingPatches link

And link to the newly-local DCO.

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

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>

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

Luis R. Rodriguez [1] has been trying to get information about the
licensing of the Linux kernel's DCO [2] for a while now [3,4], and it
looks like the Linux Foundation just made their view explicit [5,6,7].
This clarifies the copyright and licensing of Linus' two patches:

* 857a183 Update DCO ("signoff") rules to 1.1
* 991bd2e Start documenting the sign-off procedure in SubmittingPatches

From the whois information, developercertificate.org is pretty recent:

  $ whois developercertificate.org
  Domain Name: DEVELOPERCERTIFICATE.ORG
  Domain ID: D170689185-LROR
  Creation Date: 2014-01-15T02:54:55Z
  Updated Date: 2014-01-17T22:11:12Z
  ...
  Name Server: NS2.LINUX-FOUNDATION.ORG
  Name Server: NS1.LINUX-FOUNDATION.ORG

Now that this has an upstream source and it's own license (verbatim
copies only), I'm putting this file in its own branch.  Downloaded
just now:

  $ wget -S -O developer-certificate-of-origin http://developercertificate.org/
  --2014-01-24 15:46:21--  http://developercertificate.org/
  Resolving developercertificate.org... 140.211.169.4
  Connecting to developercertificate.org|140.211.169.4|:80... connected.
  HTTP request sent, awaiting response...
    HTTP/1.1 200 OK
    Server: nginx
    Date: Fri, 24 Jan 2014 23:46:58 GMT
    Content-Type: text/html; charset=UTF-8
    Connection: keep-alive
    Last-Modified: Fri, 17 Jan 2014 23:02:25 GMT
    ETag: "5c188d-6c5-4f0328910e8f0"
    Accept-Ranges: bytes
    Content-Length: 1733
  Length: 1733 (1.7K) [text/html]
  Saving to: ‘developer-certificate-of-origin’

  2014-01-24 15:46:21 (112 MB/s) - ‘developer-certificate-of-origin’ saved [1733/1733]

After which I stripped out the HTML, leaving just the DCO text.

[1]: http://www.do-not-panic.com/
[2]: https://www.kernel.org/doc/Documentation/SubmittingPatches
[3]: http://thread.gmane.org/gmane.linux.kernel/1397613
[4]: http://thread.gmane.org/gmane.linux.kernel/1492612
[5]: http://article.gmane.org/gmane.linux.kernel.wireless.general/118696
[6]: http://article.gmane.org/gmane.linux.kernel/1635433
[7]: http://developercertificate.org/

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

CONTRIBUTING.md: point to external docs on GitHub

This translates CONTRIBUTING (from the `contributing` branch) into
Markdown using a GitHub URL for the link.  Merging this into your
project will set it up to use GitHub's CONTRIBUTING infrastructure,
and will be used to notify users creating issues and pull requests
[1].

GitHub's blob URL syntax is [2]:

  https://github.com/<user>/<project>/blob/<commit-SHA-1>/Path/To/File

Like CONTRIBUTING, CONTRIBUTING.md is also released under the CC0
Universal license (see the `license` branch for full text).

[1]: https://github.com/blog/1184-contributing-guidelines
[2]: https://help.github.com/articles/how-do-i-get-a-permanent-link-from-file-view-to-permanent-blob-url

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

CONTRIBUTING: point to external docs (for non GPLv2= projects)

If a project wants to use the DCO/s-o-b workflow, but can't because of
license incompatibility, they can include this blurb pointing towards
the external documentation.  To avoid licensing issues with this
CONTRIBUTING file itself, I'm releasing it under the Creative Commons
CC0 1.0 Universal license (see the `license` branch for full text).

If you use this in your project, you'll probably want to adjust the
URL to point to somewhere more dependable.  It's annoyingly long, but
you should include the blob hash (or a higher level hash like the
commit hash) in your URL to make it absolutely clear which version of
the documentation you were using in your project at a particular time.

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