update DCO, no legal name needed (#1914)

* update DCO, no legal name needed

* add a changelog entry, if needed

* add necessary fullstop for style guide

---------

Co-authored-by: Josh Simmons <git@josh.tel>

CONTRIBUTING.rst

@@ -165,23 +165,6 @@ include the line in your commit or pull request comment::
 
     Signed-off-by: Your Name <your@email.example.org>
 
-We accept contributions under a legally identifiable name, such as
-your name on government documentation or common-law names (names
-claimed by legitimate usage or repute). Unfortunately, we cannot
-accept anonymous contributions at this time.
-
 Git allows you to add this signoff automatically when using the ``-s``
 flag to ``git commit``, which uses the name and email set in your
 ``user.name`` and ``user.email`` git configs.
-
-Private sign off
-~~~~~~~~~~~~~~~~
-
-If you would like to provide your legal name privately to the Matrix.org
-Foundation (instead of in a public commit or comment), you can do so by emailing
-your legal name and a link to the pull request to dco@matrix.org. It helps to
-include "sign off" or similar in the subject line. You will then be instructed
-further.
-
-Once private sign off is complete, doing so for future contributions will not
-be required.

changelogs/internal/newsfragments/1914.clarification

@@ -0,0 +1 @@
+The Matrix.org Foundation no longer requires "real" or "legally identifiable" names in order to contribute to projects.