chore: tweak docs

Author: mdjastrzebski

website/docs/MigrationV12.md

@@ -56,10 +56,6 @@ Historically `container` was supposed to mimic the [RTL's container](https://tes
 
 RNTL v12 introduces `root` API as an alternative that returns a root **host** element. The difference between `root` and `UNSAFE_root` properties is that that `root` will always represents a host element, while `UNSAFE_root` will typically represent a composite element.
 
-# All changes
-
-* TODO
-
 # Full Changelog
-https://github.com/callstack/react-native-testing-library/compare/v11.5.2...v12.0.0
+https://github.com/callstack/react-native-testing-library/compare/v11.5.2...v11.5.2...v12.0.0-rc.0