Point out you can use --bless to update allow list for removed entries

Author: jieyouxu

src/tools/tidy/src/run_make_tests.rs

@@ -80,7 +80,8 @@ pub fn check(tests_path: &Path, src_path: &Path, bless: bool, bad: &mut bool) {
             tidy_error!(
                 bad,
                 "Makefile `{}` no longer exists and should be removed from the exclusions in \
-                `src/tools/tidy/src/allowed_run_make_makefiles.txt`",
+                `src/tools/tidy/src/allowed_run_make_makefiles.txt`, you can run --bless to update \
+                the allow list",
                 p.display()
             );
         }