docs: add note about regexmaanger issue

renovate-bot.md

@@ -152,3 +152,4 @@ module "project_services" {
   source = "git::https://gitlab.com/gitlab-com/gl-security/security-operations/infrastructure-security-public/oidc-modules.git//terraform-modules/gcp-oidc?ref=2cb4111e026b3a18ff1271a4665b3015a278ea22"
 }
 ```
+**Note**: The `regexManager` used to support this is a temporary workaround until Renovate supports this natively. See [this issue](https://github.com/renovatebot/renovate/issues/23248) for more details and up-to-date status.