Update what's new for 8.1 release (#2562)

Author: Pessimistress

docs/whats-new.md

@@ -1,5 +1,13 @@
 # What's new
 
+## react-map-gl v8.1
+
+Release date: Oct 2025
+
+The core logic in the Mapbox GL JS wrapper has been rewritten to use [Proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) to intercept camera updates. We expect the new approach to improve camera synchronization between the native controller and React props when terrain and/or non-mercator projections are used. See more backgrounds in [#2514](https://github.com/visgl/react-map-gl/pull/2514).
+
+The Maplibre wrapper is unaffected by this change.
+
 ## react-map-gl v8.0
 
 Release date: Jan 2025