docs(kernel): clarify missing-file exception contract

Signed-off-by: Aakash Saravanan <aakash.saravanan@databricks.com>

Author: aakash-saravanan-db

src/databricks/sql/backend/kernel/_errors.py

@@ -13,8 +13,7 @@
 - Anything else — ``TypeError`` / ``OverflowError`` /
   ``ValueError`` from PyO3 argument conversion, or arbitrary
   extension-internal Python errors. These would otherwise propagate
-  raw to connector callers, breaking the DB-API contract that says
-  "only PEP 249 exception types cross the boundary". Wrapped in
+  raw to connector callers. Wrapped in
   ``OperationalError`` here.
 
 Local missing transfer files use the built-in ``FileNotFoundError`` class;