Scope and behavior of "type nickname" are not clear #91

Docstub currently supports configuring "type nicknames" in its configuration. This term and its behavior is currently not well defined at all.

Currently, type nicknames are used to create aliases for "qualnames" or "type names". However, neither the name or description make that very clear. Instead users might infer that it can be used to as a synonym for full doctypes.

Review if this scope is something we want to stick with. With the current implementation, nicknames can not be used to substitute full doctypes. For example, nicknaming list[str] to Messages won't work. If we broaden the scope and capabilities in this way, I think "type nickname" would be fine as a term.