Add task decorator to fabric example

Author: Steve Pulec

docs/scenarios/admin.rst

@@ -20,10 +20,11 @@ and restart the application server.
 
 ::
 
-    from fabric.api import env, cd, run, prefix
+    from fabric.api import cd, env, prefix, run, task
 
     env.hosts = ['my_server1', 'my_server2']
 
+    @task
     def deploy():
         with cd('/var/www/project-env/project'):
             with prefix('. ../bin/activate'):