feat(k8s): update doc

Author: bene2k1

containers/kubernetes/how-to/connect-cluster-kubectl.mdx

@@ -82,4 +82,39 @@ If you have not set up the Scaleway CLI yet:
 
 <Message type="tip">
   Refer to our complete [Documentation for `scw k8s`](https://github.com/scaleway/scaleway-cli/blob/master/docs/commands/k8s.md) to learn more about all available commands to manage your Kubernetes cluster using `scw`.
-</Message>
+</Message>
+
+
+## Revoking user access to the Kubernetes cluster
+
+When a user loses access rights (e.g., departs from the Organization), the Kubernetes administrator must take steps to revoke their access to the cluster.
+This is typically done by modifying IAM settings, such as adjusting policies or deleting the user’s credentials.
+
+### Steps to revoke access
+
+To revoke a user's access to the cluster, ensure that any API keys associated with the user are no longer granted permission. Here are the steps you can take:
+
+#### Delete the API key
+   - Locate the API key associated with the user.
+   - Remove the key to immediately revoke access.
+
+#### Modify IAM policies
+   - Adjust the IAM policy linked to the API key to limit or remove its permissions.
+
+#### Reassign the user to a restricted group
+   - Transfer the principal (application or user) to a group with reduced permissions that does not allow cluster access.
+
+#### Delete the Principal
+   - Permanently remove the user or application from the IAM system to ensure no further access is possible.
+
+### Revoking kubeconfig access
+
+To permanently revoke `kubeconfig` access via IAM:
+
+- **Delete the API Key**: This will ensure that the user's `kubeconfig` file becomes invalid immediately.
+- **Delete the Principal**: Removing the user or application guarantees that no further access can be gained, even if residual configurations exist.
+
+<Message type="note">
+  - Be cautious when modifying IAM policies to avoid unintended access issues for other users or services.
+  - Regularly audit IAM settings and API keys to ensure compliance with organizational security policies.
+</Message>