multidomain and default_domain options should be independent and configurable

Change-Id: I4af2a8a0b43eb3e1fd1a52ba8122293a19861b03
diff --git a/README.rst b/README.rst
index afebedb..afd5dce 100644
--- a/README.rst
+++ b/README.rst
@@ -35,6 +35,16 @@
         mail:
           host: '127.0.0.1'
 
+Multidomain setup for horizon
+
+.. code-block:: yaml
+
+    horizon:
+      server:
+        enabled: true
+        default_domain: MYDOMAIN
+        multidomain: True
+
 Simple branded horizon
 
 .. code-block:: yaml