CLI/deps reference: add examples of help/doc usage

[seancorfield]

There are no examples of how to use help/doc or help/dir. Their use with tools is not intuitive.

clojure -A:deps -Tnew help/dir

That lists functions in the default namespace of the installed tool (new, which has clj-new as the default namespace).

clojure -X:deps:some-tool help/dir

That lists functions in the default namespace of the tool declared under the :some-tool alias in your deps.edn file.