Add docs for 2.16 breaking changes (#4996)

Author: matthchr

docs/hugo/content/guide/breaking-changes/breaking-changes-v2.16.0.md

@@ -0,0 +1,12 @@
+---
+title: "v2.16.0 Breaking Changes"
+linkTitle: "v2.16.0"
+weight: -55  # This should be 5 lower than the previous breaking change document
+---
+## Breaking changes
+
+* Removed containerservice v1api20210501 v1api20231102preview api verisons. This was required to fit the new versions in the CRD. See [number of versions supported in a CRD](https://azure.github.io/azure-service-operator/guide/crd-management/#number-of-versions-supported-in-a-crd). If you allow the operator to manage its own CRDs via `--crd-pattern`, no action is needed the operator will take care of removing these versions. If you manage the CRD versions yourself, you'll need to run [asoctl clean crds](https://azure.github.io/azure-service-operator/tools/asoctl/#clean-crds) before upgrading.
+
+## Upcoming breaking changes
+
+* Will remove containerservice fleet API version v1api20230315preview in the next release of ASO (v2.17)

docs/hugo/content/guide/crd-management.md

@@ -151,8 +151,7 @@ For manually installed CRDs, [`asoctl clean crds`]( {{< relref "asoctl#clean-crd
 CRDs for upgrade when a CRD version that was previously a storage version was removed.
 
 For ASO managed CRDs, ASO will automatically clean up the old storage versions when it's upgraded to the new version
-that removed those CRDs. **Note:** This is not yet implemented, it is being tracked by 
-[#4376](https://github.com/Azure/azure-service-operator/issues/4376).
+that removed those CRDs.
 
 ## Best Practices