Support typed.clojure/doc-clj when a namespace is tagged with ^:typed.clojure

[Olical]

Typed Clojure has special doc forms that explain more things about types, we should detect a ^:typed.clojure tagged namespace and swap out the doc implementation. Thanks for @frenchy64 for telling me about this part of the system!

This will make it so Conjure's doc lookup can explain types for you. This should go hand in hand with https://github.com/Olical/background-check