improve comment

sqlmesh/core/plan/common.py

@@ -28,6 +28,7 @@ def is_breaking_kind_change(old: Snapshot, new: Snapshot) -> bool:
         return True
     if not new.is_model or not old.is_model:
         # If neither are models, then we don't need to rebuild
+        # Note that the remaining checks only apply to model snapshots
         return False
     if old.virtual_environment_mode != new.virtual_environment_mode:
         # If the virtual environment mode has changed, then we need to rebuild