Added support for password-protected registries

Related-Prod: PROD-32890
Change-Id: I92f543da94223e746d25b48d20f344d694fcb6cc
diff --git a/README.rst b/README.rst
index 2157a2b..f7a6313 100644
--- a/README.rst
+++ b/README.rst
@@ -334,6 +334,33 @@
         - container: f020d0d3efa8
         - service: contrail-control
 
+Use registry that requires authentication
+=========================================================
+
+* Define private Docker registry and credentials for it:
+
+  .. code-block:: yaml
+
+    docker:
+      host:
+        insecure_registries:
+          - 192.168.0.254:5000
+      registry:
+        my_registry:
+          address: 192.168.0.254:5000
+          user: registry_user
+          password: registry_password
+
+* Specify that services in stack require registry with authentication
+
+  .. code-block:: yaml
+
+    docker:
+      client:
+        stack:
+          myapp:
+            registry_auth: True
+
 **Read more**
 
 * https://docs.docker.com/installation/ubuntulinux/