Updates mirroring feature release note (quay#1418)

Co-authored-by: Steven Smith <[email protected]>

Author: stevsmit

modules/rn_3_15_0.adoc

@@ -19,7 +19,7 @@ The following features have been added with {productname} 3.15.1.
 [id="v2-ui-mirroring-tab"]
 ==== v2 UI mirroring tab
 
-Previously, mirroring via the {productname} UI was only available when using the legacy UI. With this update, a *Mirroring* tab has been added to the {productname} v2 UI. This tab is available under the *Repositories* page of your registry.
+With this update, a *Mirroring* tab has been added to the {productname} v2 UI. Although the *Mirroring* tab exists, it is not functionally ready for use. You should continue using the v1 UI when mirroring a repository.
 
 For more information, see link:https://docs.redhat.com/en/documentation/red_hat_quay/3/html/manage_red_hat_quay/repo-mirroring-in-red-hat-quay[Repository mirroring].