checktools.sh: add link to issue for more context about disabled Miri tests

Author: RalfJung

src/ci/docker/host-x86_64/x86_64-gnu-tools/checktools.sh

@@ -59,6 +59,7 @@ case $HOST_TARGET in
     # "error: cannot produce cdylib for ... as the target ... does not support these crate types".
     # Only run "pass" tests, which is quite a bit faster.
     #FIXME: Re-enable this once CI issues are fixed
+    # See <https://github.com/rust-lang/rust/issues/127883>
     #python3 "$X_PY" test --stage 2 src/tools/miri --target aarch64-apple-darwin --test-args pass
     #python3 "$X_PY" test --stage 2 src/tools/miri --target i686-pc-windows-gnu --test-args pass
     ;;