Add "Doc owners" to top-5 wanted list

As requested, here is an example top-5-help-wanted list item:
documentation owners.

Change-Id: Ib806a2b241050c63efed10241a401d7c6869b063

reference/top-5-help-wanted.rst

@@ -21,4 +21,30 @@ out to the TC sponsor, or the PTL of the affected project.
 
 .. _`tragedy of the commons`: https://en.wikipedia.org/wiki/Tragedy_of_the_commons
 
-(insert items here)
+
+1. Documentation owners
+=======================
+
+The #1 pain point in OpenStack, especially for new potential adopters, is
+complexity. While cutting down complexity everwhere we can is critical,
+proper documentation is essential in addressing that complexity. It directly
+benefits operators and users of OpenStack, but also facilitates ramping up
+new direct contributors to the project itself.
+
+The documentation team has been struggling with limited resources since the
+dawn of OpenStack, despite the heroic efforts of previous team members. An
+ambitious `plan`_ to further decentralize the Documentation team (and turn it
+into a guidance and mentoring support team) has been outlined. To be
+successful, this plan requires project teams to own their own documentation,
+which means that the role of documentation owners will be critical.
+
+Volunteers for this role will in the short term drive this ambitious
+transition, by being members of their project team and members of the new
+decentralized documentation team. On the long-term they will become a
+reference go-to person in their project, and respected mentors in the
+OpenStack community.
+
+Interested? Contact the Documentation PTL (asettle) or the TC sponsor for
+this item (dhellmann).
+
+.. _`plan`: https://review.openstack.org/#/c/472275/