Document e2e test timeout changes in v1.11-to-v1.12 migration doc

Signed-off-by: Stefan Büringer buringerst@vmware.com

Author: sbueringer

docs/book/src/developer/providers/migrations/v1.11-to-v1.12.md

@@ -28,6 +28,13 @@ maintainers of providers and consumers of our Go API.
 
 * `util.IsOwnedByObject`, `util.IsControlledBy` and `collections.OwnedMachines` now also require `schema.GroupKind` as input parameter.
   `schema.GroupKind` is needed for cases where typed objects are passed in because controller-runtime does not guarantee that GVK is set on typed objects.
+* Various Cluster API e2e tests with Kubernetes upgrades now use the `wait-control-plane-upgrade` and `wait-machine-deployment-upgrade` timeouts.
+  If you are running Cluster API e2e tests with upgrades you have to configure the timeouts in your e2e test configuration file, otherwise 
+  the e2e tests will use `1s` timeout which will lead to test failures. Example: 
+  ```yaml
+  default/wait-control-plane-upgrade: ["15m", "10s"]
+  default/wait-machine-deployment-upgrade: ["10m", "10s"]
+  ```
 
 ### Suggested changes for providers