DOC: Update list of maintained Qt branches
@jcfr This updates the Welcome branch page with latest supported branches. This specifically includes the adding of the Qt 5.15.16 branch to the welcome page.
I have just pushed this new branch with updates and patches to successfully build Qt. I was specifically testing building it on an M2 Pro Mac Mini with latest macOS and build tools. I added to that branch's readme information regarding building for the x86_64 architecture while on the Apple Silicon arm64 architecture. Please take a look and make changes as you see fit on this new branch.
Upon having Build-qt.sh download and with the patch directory downloaded next to it, the following build execution completed on my M2 Pro Mac Mini in 2hr45min.
./Build-qt.sh -a x86_64 -s macosx15.2 -d 13 -j 4