For renaming the master branch to main, I've got a veritable smorgasbord of PRs to do things like update links in Docs/READMEs/CONTRIBUTING files. I did this with one massive find/replace that I manually went through one at a time, so community review is important here. If anyone has any free time and wants something easy to review and/or merge, check out the list of PRs linked to
https://github.com/Islandora/documentation/issues/1595 All you have to do is make sure I didn't miss any or accidentally replace master with main when I shouldn't have.