[Bug web/64549] New: Add a 404 page

[quentin at pradet dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64549

            Bug ID: 64549
           Summary: Add a 404 page
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: web
          Assignee: unassigned at gcc dot gnu.org
          Reporter: quentin at pradet dot me

gcc.gnu.org doesn't have a 404 page, and the default Apache 404 page is a bit
terse. See https://gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html.

(This bug was originally reported to the www.gnu.org webmasters. Feel free to
close it if you don't think it's an issue.)