Port ansible doc for plugins to use DOCUMENTATION variables

* Using docstrings conflicts with the standard use of docstrings
* PYTHON_OPTIMIZE=2 will omit docstrings.  Using docstrings makes future
  changes to the plugin and module code subject to the requirement that we
  ensure it won't be run with optimization.

lib/ansible/plugins/connection/local.py

@@ -15,8 +15,10 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
-'''
-DOCUMENTATION:
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+DOCUMENTATION = '''
     connection: local
     short_description: execute on controller
     description:
@@ -27,9 +29,6 @@ DOCUMENTATION:
         - The remote user is ignored, the user with which the ansible CLI was executed is used instead.
 '''
 
-from __future__ import (absolute_import, division, print_function)
-__metaclass__ = type
-
 import os
 import shutil
 import subprocess