Merge branch 'hchouraria-docs-cluster-delete-api-no-cleanup-behavior' into 'master'

Clarify cluster deletion behavior in APIs

See merge request gitlab-org/gitlab!85913

doc/api/group_clusters.md

@@ -315,7 +315,7 @@ Example response:
 ## Delete group cluster
-Deletes an existing group cluster.
+Deletes an existing group cluster. Does not remove existing resources within the connected Kubernetes cluster.
 ```plaintext
 DELETE /groups/:id/clusters/:cluster_id

doc/api/instance_clusters.md

@@ -290,7 +290,7 @@ Example response:
 ## Delete instance cluster
-Deletes an existing instance cluster.
+Deletes an existing instance cluster. Does not remove existing resources within the connected Kubernetes cluster.
 ```plaintext
 DELETE /admin/clusters/:cluster_id

doc/api/project_clusters.md

@@ -388,7 +388,7 @@ Example response:
 ## Delete project cluster
-Deletes an existing project cluster.
+Deletes an existing project cluster. Does not remove existing resources within the connected Kubernetes cluster.
 ```plaintext
 DELETE /projects/:id/clusters/:cluster_id