cumin: add example for matching resources and use newer 'role'-based class

The monitoring example for matching on an included class uses the legacy
`roles` module. To make this example live longer, let's get rid of the
example based on the legacy module.

There's currently no example for how we can match on the presence of a
resource type. It's useful to know that the pattern is a bit different
than how matching for classes is done.

The cumin documentation has some more examples for how to make matching
more precise by using expected parameter values on the resource types.
But we can find those out in the cumin doc. As long as we know from our
side that matching on resource types is possible.