Document xacml-pdp REST server for honolulu

Add documentation for Honolulu Maintenance Release regarding xacml-pdp
always being active.

Issue-ID: POLICY-3556
Change-Id: Ib509d3d9e4cbd7f8e85199b735da0556745dc89b
Signed-off-by: Jim Hahn <jrh3@att.com>
(cherry picked from commit a7b369ac9358351efae2bf8639e8c692951d3971)
diff --git a/docs/release-notes.rst b/docs/release-notes.rst
index 032c5a3..5e4fee3 100644
--- a/docs/release-notes.rst
+++ b/docs/release-notes.rst
@@ -67,6 +67,16 @@
     * `[POLICY-3516] <https://jira.onap.org/browse/POLICY-3516>`_ - Upgrade CDS dependency to the 1.1.5 version
 
 
+Known Limitations
+=================
+
+The APIs provided by xacml-pdp (e.g., healthcheck, statistics, decision)
+are always active.  While PAP controls which policies are deployed to a
+xacml-pdp, it does not control whether or not the APIs are active.
+In other words, xacml-pdp will respond to decision requests, regardless
+of whether PAP has made it ACTIVE or PASSIVE.
+
+
 Version: 8.0.0
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