Add await explanation on non thenable

release notes/v0.50.0.md

@@ -20,6 +20,8 @@ In future releases, we are going to be moving most of the synchronous browser AP
 
 You can find a list of all the APIs that we expect to convert to async in a comment in issue [browser#428](https://github.com/grafana/xk6-browser/issues/428#issuecomment-1964020837).
 
+Awaiting on something that’s not a thenable just resolves to that value, which means you can add the `await` keyword against APIs that will become async to future proof your test scripts.
+
 ### (_optional h3_) `<big_breaking_change>` `#pr`
 
 ## New features