Typos in the yaml inventory plugin

This patch fixes up some English typos in the yaml inventory
plugin documentation.

* s/specifically/specific
* s/as/as an

Signed-off-by: Eric Brown <browne@vmware.com>

lib/ansible/plugins/inventory/yaml.py

@@ -7,7 +7,7 @@ __metaclass__ = type
 DOCUMENTATION = '''
     inventory: yaml
     version_added: "2.4"
-    short_description: Uses a specifically YAML file as inventory source.
+    short_description: Uses a specific YAML file as an inventory source.
     description:
         - "YAML based inventory, starts with the 'all' group and has hosts/vars/children entries."
         - Host entries can have sub-entries defined, which will be treated as variables.