Update migration guide

site/content/docs/5.0/migration.md

@@ -21,6 +21,10 @@ toc: true
 
 - Introduce `$enable-smooth-scroll`, which applies `scroll-behavior: smooth` globally—except for users asking for reduced motion through `prefers-reduced-motion` media query. [See #31877](https://github.com/twbs/bootstrap/pull/31877)
 
+### Forms
+
+- The longstanding [Missing border radius on input group with validation feedback bug](https://github.com/twbs/bootstrap/issues/25110) is finally fixed by adding an additional `.has-validation` class to input groups with validation.
+
 ## v5.0.0-alpha2
 
 ### Sass