[DOCS] Identify reloadable Watcher settings #61126
Description
We need to clarify the list of Watcher settings(https://www.elastic.co/guide/en/elasticsearch/reference/master/notification-settings.html) such that the reloadable settings are clearly identified. Then a link to that page also needs to be added here: https://www.elastic.co/guide/en/elasticsearch/reference/master/secure-settings.html#reloadable-secure-settings