Implement X.509 auth for MySQL and Barbican

Change-Id: Ic724d0d3474f0d52c56638e8805b2f64dc21c120
Related-PROD: PROD-22738
diff --git a/README.rst b/README.rst
index 33aea5c..0f4e655 100644
--- a/README.rst
+++ b/README.rst
@@ -389,6 +389,28 @@
               encodeb64_payload: true
 
 
+Enable x509 and ssl communication between Barbican and Galera cluster.
+---------------------
+By default communication between Barbican and Galera is unsecure.
+
+barbican:
+  server:
+    database:
+      x509:
+        enabled: True
+
+You able to set custom certificates in pillar:
+
+barbican:
+  server:
+    database:
+      x509:
+        cacert: (certificate content)
+        cert: (certificate content)
+        key: (certificate content)
+
+You can read more about it here:
+    https://docs.openstack.org/security-guide/databases/database-access-control.html
 
 Documentation and Bugs
 ======================