Fix example where imported ssh keys contain spaces

This fixes #1521

docsite/rst/playbooks2.rst

@@ -402,7 +402,7 @@ This syntax will remain in future versions, though we will also will provide way
 is an example using the authorized_key module, which requires the actual text of the SSH key as a parameter::
 
     tasks:
-        - authorized_key name=$item key=$FILE('/keys/$user1')
+        - authorized_key name=$item key="$FILE('/keys/$user1')"
           with_items:
              - pinky
              - brain