Make identifiers clickable in the rendered API docs

[vdusek]

• Make identifiers of classes, functions, methods, etc., clickable in the generated API docs.
• docs: improve API docs of all crawlers #624 (comment)

[barjin]

(Marginally) related to apify/crawlee#2717 - we might want to use something like e.g. JSDoc's {@link Dataset}. In the best case, we'd like to render clickable links both in IDEs and on the web.

I'm not sure whether this aligns with Python project documentation standards; it might need more research.