Add the RBTools 3.x intersphinx mapping for the release notes.
Review Request #12195 — Created March 22, 2022 and submitted
This adds the
rbt3.xintersphinx mapping key in the release notes,
allowing documentation in RBTools 3 to be referenced.
The 3.0 release notes have been updated to use this key.
Tested against my local dev server. Saw that the pages could be
referenced and linked to correctly.