rewrite man page in rst

Only minimal changes needed.

This was done to satisfy darko-poljak's request here:
https://github.com/ungleich/cdist/pull/360#issuecomment-263491151

cdist/conf/type/__postgres_extension/man.rst

@@ -1,7 +1,5 @@
 cdist-type__postgres_extension(7)
 =================================
-Tomas Pospisek <tpo_deb--@--sourcepole.ch>
-
 
 NAME
 ----
@@ -16,35 +14,42 @@ The object you need to pass to __postgres_extension consists of
 the database name and the extension name joined by a colon in the
 following form:
 
+.. code-block::
+
     dbname:extension
 
 f.ex.
 
+.. code-block::
+
     rails_test:unaccent
 
 
 OPTIONAL PARAMETERS
 -------------------
-state::
+state
-    Either "present" or "absent", defaults to "present"
+    either "present" or "absent", defaults to "present"
 
 
 EXAMPLES
 --------
 
---------------------------------------------------------------------------------
+.. code-block:: sh
+
     __postgres_extension           rails_test:unaccent
     __postgres_extension --present rails_test:unaccent
     __postgres_extension --absent  rails_test:unaccent
---------------------------------------------------------------------------------
 
 
 SEE ALSO
 --------
-- cdist-type(7)
+:strong:`cdist-type`\ (7), :strong:`cdist-type__postgre_database`\ (7)
-- cdist-type__postgres_database(7)
-- http://www.postgresql.org/docs/current/static/sql-createextension.html
 
+Postgres "Create Extension" documentation at: <http://www.postgresql.org/docs/current/static/sql-createextension.html>.
+
+AUTHOR
+-------
+Tomas Pospisek <tpo_deb--@--sourcepole.ch>
 
 COPYING
 -------