Add match_on option scheme in configuration.rst

Minor documentation corrections: The list of ``match_on`` options was missing ``scheme``. Also, an unneeded period appeared after URI.

Author: jshprentz

docs/configuration.rst

@@ -42,7 +42,8 @@ This can be configured by changing the ``match_on`` setting.
 The following options are available :
 
 -  method (for example, POST or GET)
--  uri (the full URI.)
+-  uri (the full URI)
+-  scheme (for example, HTTP or HTTPS)
 -  host (the hostname of the server receiving the request)
 -  port (the port of the server receiving the request)
 -  path (the path of the request)