add release notes for CAPZ v1.13.6

Author: willie-yao

CHANGELOG/v1.13.6.md

@@ -0,0 +1,18 @@
+## Changes by Kind
+
+### Bug or Regression
+
+- [`AZURE_SYNC_PERIOD`](https://azure.github.io/azure-service-operator/guide/aso-controller-settings-options/#azure_sync_period) for ASO now defaults to `1h` instead of "effectively never" ([#4782](https://github.com/kubernetes-sigs/cluster-api-provider-azure/pull/4782), [@k8s-infra-cherrypick-robot](https://github.com/k8s-infra-cherrypick-robot))
+- Don't allow fleetsMembers to have capital letters. Default fleet spec.group. ([#4820](https://github.com/kubernetes-sigs/cluster-api-provider-azure/pull/4820), [@willie-yao](https://github.com/willie-yao))
+- Use correct resource group for Bastion with custom vnet ([#4817](https://github.com/kubernetes-sigs/cluster-api-provider-azure/pull/4817), [@k8s-infra-cherrypick-robot](https://github.com/k8s-infra-cherrypick-robot))
+
+## Dependencies
+
+### Added
+_Nothing has changed._
+
+### Changed
+_Nothing has changed._
+
+### Removed
+_Nothing has changed._