Forward port 8.11.0 docs (elastic#101885)

docs/reference/migration/migrate_8_11.asciidoc

@@ -9,12 +9,61 @@ your application to {es} 8.11.
 
 See also <<release-highlights>> and <<es-release-notes>>.
 
-coming::[8.11.0]
-
 
 [discrete]
 [[breaking-changes-8.11]]
 === Breaking changes
 
-There are no breaking changes in {es} 8.11.
+The following changes in {es} 8.11 might affect your applications
+and prevent them from operating normally.
+Before upgrading to 8.11, review these changes and take the described steps
+to mitigate the impact.
+
+
+There are no notable breaking changes in {es} 8.11.
+But there are some less critical breaking changes.
+
+[discrete]
+[[breaking_811_rest_api_changes]]
+==== REST API changes
+
+[[remove_transport_versions_from_cluster_state_api]]
+.Remove `transport_versions` from cluster state API
+[%collapsible]
+====
+*Details* +
+The `transport_versions` subobject of the response to `GET _cluster/state` has been replaced by the `nodes_versions` subobject.
+
+*Impact* +
+If needed, retrieve the per-node transport versions from the `nodes_versions` subobject.
+====
+
+
+[discrete]
+[[deprecated-8.11]]
+=== Deprecations
+
+The following functionality has been deprecated in {es} 8.11
+and will be removed in a future version.
+While this won't have an immediate impact on your applications,
+we strongly encourage you to take the described steps to update your code
+after upgrading to 8.11.
+
+To find out if you are using any deprecated functionality,
+enable <<deprecation-logging, deprecation logging>>.
+
+[discrete]
+[[deprecations_811_rollup]]
+==== Rollup deprecations
+
+[[rollup_functionality_deprecated]]
+.Rollup functionality is now deprecated
+[%collapsible]
+====
+*Details* +
+<<xpack-rollup,Rollup functionality>> has been deprecated and will be removed in a future release. Previously, rollups were available in technical preview.
+
+*Impact* +
+Use <<downsampling,downsampling>> to reduce storage costs for time series data by storing it at reduced granularity.
+====