docs: Include information about the list of supported projects

This documentation is included in HACKING at the top to let
newcomers know that Patrole's testing scope is confined to the
following projects:

* Cinder
* Glance
* Keystone
* Neutron
* Nova

Depends-On: https://review.openstack.org/#/c/615394
Change-Id: I6f70a6169592fec41de67ecfed6e5ca5b9af0deb
diff --git a/HACKING.rst b/HACKING.rst
index 9868e39..3379292 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -43,6 +43,23 @@
 
 .. _extension test class: https://github.com/openstack/patrole/tree/master/patrole_tempest_plugin/tests/api/network#neutron-extension-rbac-tests
 
+Supported OpenStack Components
+------------------------------
+
+Patrole only offers **in-tree** integration testing coverage for the following
+components:
+
+* Cinder
+* Glance
+* Keystone
+* Neutron
+* Nova
+
+Patrole currently has no stable library, so reliance upon Patrole's framework
+for external RBAC testing should be done with caution. Nonetheless, even when
+Patrole has a stable library, it will only offer in-tree RBAC testing for
+the components listed above.
+
 Role Overriding
 ---------------
 
diff --git a/README.rst b/README.rst
index 5331445..713756a 100644
--- a/README.rst
+++ b/README.rst
@@ -18,9 +18,6 @@
 allowing deployments to verify that only intended roles have access to those
 APIs.
 
-Patrole currently offers testing for the following OpenStack services: Nova,
-Neutron, Glance, Cinder and Keystone.
-
 Patrole is currently undergoing heavy development. As more projects move
 toward policy in code, Patrole will align its testing with the appropriate
 documentation.
@@ -205,7 +202,11 @@
 For more information about RBAC, reference the `rbac-overview`_
 documentation page.
 
+For information regarding which projects Patrole offers RBAC testing for,
+reference the `HACKING`_ documentation page.
+
 .. _rbac-overview: https://docs.openstack.org/patrole/latest/rbac-overview.html
+.. _HACKING: https://docs.openstack.org/patrole/latest/HACKING.html#supported-openstack-components
 
 Unit Tests
 ----------