Update banner.mdx

Author: lindseywild

content/components/banner.mdx

@@ -26,8 +26,6 @@ When deciding whether to focus a banner or use a live region, consider the follo
 * Where is a user's focus when the banner appears; would focus otherwise be lost if the banner is not focused?
 * Is there already a live region on the page that can be utilized? [Dynamic live regions can have some challenges](https://github.com/github/accessibility/blob/main/docs/coaching-recommendations/toast-flash-banner/accessible-banner-prototype.md#challenges-with-dynamically-inserted-live-region), so this method requires ample testing.
 
-If you decide focusing the banner is the approach to go with, follow the [accessibility guidance in the Rails docs](https://primer.style/components/banner/rails/alpha#accessibility).
-
 Please reach out to the accessibility team if you need help determining the best approach for your use case!
 
 ### Known accessibility issues (GitHub staff only)