Add link to issue

Author: Mark-Simulacrum

compiler/rustc_query_system/src/query/plumbing.rs

@@ -594,6 +594,7 @@ fn incremental_verify_ich<CTX, K, V: Debug>(
         tcx.sess().struct_err(&format!("internal compiler error: encountered incremental compilation error with {:?}", dep_node))
             .help(&format!("This is a known issue with the compiler. Run {} to allow your project to compile", run_cmd))
             .note(&format!("Please follow the instructions below to create a bug report with the provided information"))
+            .note(&format!("See <https://github.com/rust-lang/rust/issues/84970> for more information."))
             .emit();
         panic!("Found unstable fingerprints for {:?}: {:?}", dep_node, result);
     }