Update notification-messaging.mdx

content/ui-patterns/notification-messaging.mdx

@@ -15,7 +15,7 @@ Primer messaging components:
 
 Messaging holds differing levels of prominence which can be used to determine the appropriate component to use. Most messages fall into one of the following categories, from most prominent to least:
 
-**System updates**: These types of messages originate from GitHub and are not user initiated. System announcements related to a specific product area such as a single sign-on message should use the **Banner** component. System update type messages cannot be dismissed until the issue is resolved, or may be perminent if they are purely informative.
+**System updates**: These types of messages originate from GitHub and are not user initiated. System announcements related to a specific product area such as a single sign-on message should use the **Banner** component. System update type messages cannot be dismissed until the issue is resolved, or may be perminent if they are purely informative. Global system announcements that are relevant beyond the current page use an **Announcement** (not a Primer component).
 
 **Feedback**: Communicates the result of a user action (submitting a form, toggling a setting, etc.) Feedback can be positive, negative, or a warning. Feedback is shown in either a **Banner** or **Inline message**. For forms, an inline message is used for individual field validation which may be combined with a banner if multiple fields have errors. Banners are placed at the top of the page or section they are related to, but still within the body content. Inline messages are placed near the action they are related to.