[PATCH][wwwdocs] Initial changes.html section for arm and aarch64

[Kyrylo Tkachov via Gcc-patches]

Hi all,

This patch creates the arm and aarch64 sections in the changes.html page for 
GCC 12.
Some features are common to both backends, so we use a shared section for those 
(like last year).

This list is not complete, but should work fine for a start. feel free to tell 
me if you think something else should be mentioned

Pushing to wwwdocs repo.

Thanks,
Kyrill

wwwdocs-gcc-12.patch
Description: wwwdocs-gcc-12.patch