Add cycle-highlights deadline to Stein

This adds some deadline information to the Stein schedule so teams can
plan when they need to gather these in time for inclusion.

Change-Id: I9e1a4ab132e973e97415a35b102114071ea403a8
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

doc/source/stein/schedule.rst

@@ -181,6 +181,18 @@ intermediary releases before release week. During release week, only
 final-release-critical releases will be accepted (at the discretion of the
 release team).
 
+.. _s-cycle-highlights:
+
+Cycle highlights marketing deadline
+-----------------------------------
+
+Cycle highlights need to be added to the release deliverables by this point to
+be included in any marketing release messaging. Highlights may be added after
+this point, but they will likely only be useful for historical purposes.
+
+See the `project team guide <https://docs.openstack.org/project-team-guide/release-management.html#cycle-highlights>`_
+for more details and instructions on adding these highlights.
+
 .. _s-release:
 
 Stein release

doc/source/stein/schedule.yaml

@@ -123,6 +123,7 @@ cycle:
   start: '2019-04-01'
   x-project:
     - s-finalrc
+    - s-cycle-highlights
 - end: '2019-04-12'
   name: R+0
   start: '2019-04-08'