Add one more example to "git try -h" output.

trychange.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Client-side script to send a try job to the try server. It communicates to
 the try server by either writting to a svn repository or by directly connecting
 to the server by HTTP.
 """
 
@@ skipping 34 matching lines @@
 
 EPILOG = """
 Examples:
   Send a patch directly from rietveld:
     %(prog)s -R codereview.chromium.org/1337
         --email recipient@example.com --root src
 
   Try a change against a particular revision:
     %(prog)s -r 123
 
+  Try a change including changes to a sub repository:
+    %(prog)s -s third_party/WebKit
+
   A git patch off a web site (git inserts a/ and b/) and fix the base dir:
     %(prog)s --url http://url/to/patch.diff --patchlevel 1 --root src
 
   Use svn to store the try job, specify an alternate email address and use a
   premade diff file on the local drive:
     %(prog)s --email user@example.com
             --svn_repo svn://svn.chromium.org/chrome-try/try --diff foo.diff
 
   Running only on a 'mac' slave with revision 123 and clobber first; specify
   manually the 3 source files to use for the try job:
@@ skipping 868 matching lines @@
     return 1
   except (gclient_utils.Error, subprocess2.CalledProcessError), e:
     print >> sys.stderr, e
     return 1
   return 0
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(TryChange(None, None, False))