Cherry pick trove dev docs link to stable/grizzly.

from https://review.openstack.org/#/c/39587/

Added link to the trove developer docs in the openstack-projects page

Added a link to the generated trove developer docs
(http://docs.openstack.org/developer/trove/) in the openstack-projects
page.

Change-Id: Id42f58d40b6a7acee170ca647d844430c9047caf