[Docs] Add Developer Certificate of Origin (DCO)

Add a DCO and related text to CONTRIBUTING.rst.  Also add this documentation to rtdocs.

Signed-off-by: Don Porter <[email protected]>

CONTRIBUTING.rst

@@ -75,6 +75,14 @@ In general, a |nbsp| PR should:
    testing) or cannot be easily tested (e.g., a performance fix).
 #. Follow project's `style guidelines
    <https://graphene.rtfd.io/en/latest/devel/coding-style.html>`__.
+#. Be signed-off by the author of the PR in git (i.e., using the ``git commit -s``, indicating
+   that the authors are agreeing to the terms of the `project Developer
+   Certificate of Origin <DCO>`__
+
+.. Github and RTD use different roots for resolving paths, because of
+   of .. include: in Documentation/devel/contributing.rst.  This renders as
+   a directory over file//.  Over http[s]:// we take advantage of the automatic
+   / redirect implemented in most HTTP servers. That's why DCO/ is a directory and not a file.
 
 PR Life Cycle
 ^^^^^^^^^^^^^
@@ -110,6 +118,7 @@ Before a pull request is merged, it must:
 #. Pass all CI tests
 #. Follow project's `style guidelines
    <https://graphene.rtfd.io/en/latest/devel/coding-style.html>`__.
+#. Be signed-off by the contributor.
 #. Introduce no new compilation errors or warnings
 #. Have all discussions from reviewers resolved
 #. Have a clear, concise and grammatically correct comments and commit messages.

DCO

@@ -0,0 +1,39 @@
+Developer Certificate of Origin
+===============================
+:Version: 1.1
+
+| Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+| 1 Letterman Drive
+| Suite D4700
+| San Francisco, CA, 94129
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+
+Developer's Certificate of Origin 1.1
+-------------------------------------
+
+By making a contribution to this project, I certify that:
+
+1. The contribution was created in whole or in part by me and I
+   have the right to submit it under the open source license
+   indicated in the file; or
+
+2. The contribution is based upon previous work that, to the best
+   of my knowledge, is covered under an appropriate open source
+   license and I have the right under that license to submit that
+   work with modifications, whether created in whole or in part
+   by me, under the same open source license (unless I am
+   permitted to submit under a different license), as indicated
+   in the file; or
+
+3. The contribution was provided directly to me by some other
+   person who certified (1), (2) or (3) and I have not modified
+   it.
+
+4. I understand and agree that this project and the contribution
+   are public and that a record of the contribution (including all
+   personal information I submit with it, including my sign-off) is
+   maintained indefinitely and may be redistributed consistent with
+   this project or the open source license(s) involved.

Documentation/devel/DCO/index.rst

@@ -0,0 +1 @@
+.. include:: ../../../DCO

Documentation/index.rst

@@ -69,6 +69,7 @@ Table of Contents
    :maxdepth: 1
 
    devel/contributing
+   devel/DCO/index
    devel/howto-doc
    devel/coding-style
    devel/setup