add circus doc in monitoring tools.

doc/site/deploy.rst

@@ -129,6 +129,18 @@ Monitoring
     will fork-exec which creates an unmonitored process and generally just
     confuses the monitor services.
 
+Circus
+++++++
+
+`Circus <http://circus.readthedocs.org/en/latest/index.html>`_ can be
+used to monitor gunicorn. A simple configuration is::
+
+    [watcher:mywebapp]
+    cmd = gunicorn -w 3 test:app
+    working_dir = /Users/benoitc/work/friendpaste2/src/gunicorn/examples
+    send_hup = true
+
+Then you can easily manage Gunicorn using the ``circusctl`` command.
 
 Runit
 +++++