also show an example to query by parameter value

howto/cumin.md

@@ -223,7 +223,19 @@ built catalog:
 
 To run against only the dal ganeti cluster nodes:
 
-    cumin 'R:class=role::ganeti::dal' uptime
+    cumin 'C:role::ganeti::dal' uptime
+
+Or, the same command using the `O:` shortcut:
+
+    cumin 'O:ganeti::dal' uptime
+
+To query any host that applies a certain profile:
+
+    cumin 'P:opendkim' uptime
+
+And to query hosts that apply a certain profile with specific parameters:
+
+    cumin 'P:opendkim%mode = sv' uptime
 
 Any Puppet fact or class can be queried that way. This also serves as
 a ad-hoc interface to query PuppetDB for certain facts, as you don't