Add TC-owned project-team-guide repo

The TC has a subgroup working on documentation for project teams
as OpenStack grows to encompass more projects.  This is a repo to
host that documentation.

Change-Id: Ib4f9934ca6d0946ca3f633f95c9336227bd6de28
Depends-On: I46292749d645f5f8e99c4f52c975c79bb446c6db

reference/technical-committee-repos.yaml

@@ -3,3 +3,4 @@ Technical Committee:
   - repo: openstack/governance
   - repo: openstack/openstack-specs
   - repo: openstack/api-wg
+  - repo: openstack/project-team-guide