update toc

Author: RaunakShah

keps/sig-storage/3141-prevent-volume-mode-conversion/README.md

@@ -77,8 +77,10 @@ SIG Architecture for cross-cutting KEPs).
   - [Changes to Snapshot Controller](#changes-to-snapshot-controller)
   - [Changes to external-provisioner](#changes-to-external-provisioner)
   - [Test Plan](#test-plan)
-    - [Unit tests](#unit-tests)
-    - [E2E tests](#e2e-tests)
+      - [Prerequisite testing updates](#prerequisite-testing-updates)
+      - [Unit tests](#unit-tests)
+      - [Integration tests](#integration-tests)
+      - [e2e tests](#e2e-tests)
   - [Graduation Criteria](#graduation-criteria)
     - [Alpha](#alpha)
     - [Alpha -> Beta](#alpha---beta)