Unhardcodig HORIZON_CONFIG dictionary

The patch makes possible to change parameters inside
HORIZON_CONFIG along with password_validator and password_validator_help.

Change-Id: I9df6ab83181429ee6303bba987e7387dd0c9d953
Related-PROD: PROD-27459
diff --git a/README.rst b/README.rst
index a79e1f3..bd06ba5 100644
--- a/README.rst
+++ b/README.rst
@@ -55,6 +55,30 @@
         default_dashboard: 'admin'
         help_url: 'http://doc.domain.com'
 
+Dashboard settings with HORIZON_CONFIG dictionary:
+
+.. code-block:: yaml
+
+    horizon:
+      server:
+        enabled: true
+        horizon_config:
+          user_home: "openstack_dashboard.views.get_user_home"
+          ajax_queue_limit: 10
+          auto_fade_alerts:
+            delay: 3000
+            fade_duration: 1500
+            types:
+              - alert-success
+              - alert-info
+          help_url: "http://docs.openstack.org"
+          modal_backdrop: "static"
+          disable_password_reveal: True
+          password_validator:
+            regex: "^.{8,18}$"
+            help_text: "Password must be between 8 and 18 characters."
+            password_autocomplete: "off"
+
 Horizon with policy files metadata. With source mine you can obtain real
 time policy file state from targeted node (OpenStack control node),
 provided you have policy file published to specified grain key. Source