Adding an ability to set target for mysql user grant.

Change-Id: I793a25750c39f70aa26415e7e6a95100b33373fe
diff --git a/README.rst b/README.rst
index 3f603ff..552c50c 100644
--- a/README.rst
+++ b/README.rst
@@ -36,6 +36,7 @@
               password: 'password'
               host: 'localhost'
               rights: 'all privileges'
+              target: '*.*'
 
 
 MySQL replication master with SSL