doc/arch/m68k.rst: Update toolchain comment

The old wiki page has not exited for quite some time, update to note
what we build with in CI at least.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/arch/m68k.rst b/doc/arch/m68k.rst
index 8474ece..de7eb38 100644
--- a/doc/arch/m68k.rst
+++ b/doc/arch/m68k.rst
@@ -82,9 +82,9 @@
 Adopted toolchains
 ------------------
 
-Please check:
-https://www.denx.de/wiki/U-Boot/ColdFireNotes
-
+Currently the `kernel.org cross-development toolchains
+<https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/>`_ are
+used in the project CI builds.
 
 ColdFire specific configuration options/settings
 ------------------------------------------------