[doc] Add documentation on external contributions

doc/contribute.rst

+.. Copyright © 2022 Idiap Research Institute <contact@idiap.ch>
+..
+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+.. _mednet.contribute:
+
+===================================
+ Getting Involved and Contributing
+===================================
+
+We will happily accept external contributions, but substantial contributions
+require a signed Contributor or `Copyright License Agreement <cla_>`_ (CLA).
+Our CLA, based on `Project Harmony`_, leaves copyright with you (the
+contributor), but allows us to relicense the code, with a restriction based on
+the license the contribution was made under.
+
+Contact our `Technology Transfer Officer <tto_>`_ to get a copy of the CLA_ for
+this project.  If you work for a company and your contributions are tied to
+your job, ensure you have the legal right to sign this CLA, or refer to the
+responsible person during your e-mail exchange with our TTO_.
+
+
+.. include:: links.rst

doc/index.rst

@@ -57,6 +57,7 @@ User Guide
    cli
    config
    api
+   contribute
 
 
 Indices and tables

doc/links.rst

@@ -5,8 +5,11 @@
 .. place re-used URLs here, then include this file
 .. on your other RST sources.
 
-.. _conda: https://conda.io
 .. _idiap: http://www.idiap.ch
+.. _cla: https://en.wikipedia.org/wiki/Contributor_License_Agreement
+.. _project harmony: http://www.harmonyagreements.org/
+.. _tto: mailto:tto@idiap.ch
+.. _conda: https://conda.io
 .. _python: http://www.python.org
 .. _pip: https://pip.pypa.io/en/stable/
 .. _mamba: https://mamba.readthedocs.io/en/latest/index.html