Update GitLab page content on the how to section with a note

Author: petrisorcoderabbit

docs/integrations/saas-gitlab.md

@@ -13,6 +13,13 @@ The CodeRabbit default user is already set up in GitLab SaaS and will be added t
 
 If your organization prefers to use an organization user, you can create a new user in GitLab and generate a Personal Access Token for that user, following [our recommendations](#recommendations).
 
+:::note
+
+Keep in mind that if you want to change the review user, you can either disable the organization user or add a new user via the CodeRabbit UI. However, this will require manually removing the previous user from the projects and associated webhooks.
+Afterward, you will need to reinstall the CodeRabbit app for each project.
+
+:::
+
 ## GitLab Access Tokens
 To interact with the GitLab API, a **Personal Access Token** is required. This token can either be generated by using our default CodeRabbit user or by creating a **Personal Access Token** from one of your existing users.