[docs] add more uses cases to node-selector service annotation

Author: kayrus

docs/openstack-cloud-controller-manager/using-openstack-cloud-controller-manager.md

@@ -155,7 +155,7 @@ The options in `Global` section are used for openstack-cloud-controller-manager
 * `application-credential-secret`
   The secret of an application credential to authenticate with.
 * `tls-insecure`
-  If set to `true`, then the server’s certificate will not be verified. Default is `false`.
+  If set to `true`, then the server's certificate will not be verified. Default is `false`.
 
 ###  Networking
 
@@ -265,6 +265,12 @@ Although the openstack-cloud-controller-manager was initially implemented with N
   node-selector="env, region=default"
   ```
 
+  See also the Kubernetes annotation [`node.kubernetes.io/exclude-from-external-load-balancers`](https://kubernetes.io/docs/reference/labels-annotations-taints/#node-kubernetes-io-exclude-from-external-load-balancers). When this annotation is set to `true`, the node is excluded from the load balancer pool.  
+
+  This annotation also triggers the Cloud Controller Manager to execute the `EnsureLoadBalancer` method to reconcile the LoadBalancer. If a node was already part of the cluster and its label was later modified after the service's `node-selector` annotation was changed, you can explicitly assign `node.kubernetes.io/exclude-from-external-load-balancers: "false"` to a node to force the Cloud Controller Manager to reconcile the LoadBalancer pool.
+
+  For example, if a service has `node-selector="env=production"` and a node is labeled `env=development`, updating the node's label to `env=production` will not automatically add it to the LoadBalancer pool. In such cases, setting `node.kubernetes.io/exclude-from-external-load-balancers: "false"` to the node ensures that the Cloud Controller Manager re-evaluates the node's eligibility and updates the LoadBalancer configuration accordingly.
+
 * `cascade-delete`
   Determines whether or not to perform cascade deletion of load balancers. Default: true.