Deprecate enable_rbac configuration option

The ``[patrole].enable_rbac`` option is deprecated and will be removed
during the "S" release. This is a legacy option that was meaningful
downstream when Patrole was a suite of tests inside Tempest itself. Now
that Patrole exists upstream as a Tempest plugin, it is paradoxical to
install the Patrole plugin yet have an option that allows all Patrole
tests to be skipped. This option is at odds with current Patrole
architecture.

To skip RBAC tests going forward, with Patrole Tempest plugin already
installed, use an appropriate regex.

Change-Id: I0cc39184c7891fb9133a45488a36ba220592915f
diff --git a/releasenotes/notes/deprecate-enable-rbac-option-1e499bb0914cdee8.yaml b/releasenotes/notes/deprecate-enable-rbac-option-1e499bb0914cdee8.yaml
new file mode 100644
index 0000000..7354c4f
--- /dev/null
+++ b/releasenotes/notes/deprecate-enable-rbac-option-1e499bb0914cdee8.yaml
@@ -0,0 +1,13 @@
+---
+deprecations:
+  - |
+    The ``[patrole].enable_rbac`` option is deprecated and will be removed
+    during the "S" release. This is a legacy option that was meaningful
+    downstream when Patrole was a suite of tests inside Tempest itself. Now
+    that Patrole exists upstream as a Tempest plugin, it is paradoxical to
+    install the Patrole plugin yet have an option that allows all Patrole
+    tests to be skipped. This option is at odds with current Patrole
+    architecture.
+
+    To skip RBAC tests going forward, with Patrole Tempest plugin already
+    installed, use an appropriate regex.