[Bug other/82383] Some new toplevel directories are not documented

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82383

--- Comment #3 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #2)
> libcilkrts can be removed from the list of directories to document, since it
> no longer exists in trunk.

Same with libmpx now too.