Documentation/llvm: update IRC location

Documentation/llvm: update IRC location

This should have been done with commit 85fc1fffe6a4 ("MAINTAINERS: update
ClangBuiltLinux IRC chat") but I did not realize it was in two separate
spots.

Link: https://lkml.kernel.org/r/20210825211823.6406-3-nathan@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>