Update README.rst

Author: lorin

README.rst

@@ -13,7 +13,7 @@ These are variables that are always defined by ansible.
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 Parameter                      Description
 ============================   =========================================================================================================================================================================================================
-hostvars                       A dict whose keys are Ansible host names and values are variable names
+hostvars                       A dict whose keys are Ansible host names and values are dicts that map variable names to values
 groups                         A dict whose keys are Ansible group names and values are list of hostnames that are members of the group. Includes ``all`` and ``ungrouped`` groups: ``{"all": [...], "web": [...], "ungrouped": [...]}``
 inventory_hostname             Name of the current host as known by ansible.
 ============================   =========================================================================================================================================================================================================