[doc] Update thread information in developer docs

Summary:
This is a backport of Core PR18645

Note: the StartNode line was removed in PR17539 (not yet backported)

Test Plan: Clicked on all the URLs to check that they work.

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8930