Update entitlement files and other signing related pieces for 9.5 changes and include fixups

We have a bunch of scripts in our tor-browser-build repo (in tools/signing) which show how we do currently a bunch of signing related jobs.

We should update the things that need update for 9.5/10.0a1 (probably both on master and, where applicable, on maint-9.5 for stable) and go over the README again (typo fixing).