Update whats-new

Author: mgunyho

doc/whats-new.rst

@@ -335,6 +335,8 @@ New Features
 - Added ability to save ``DataArray`` objects directly to Zarr using :py:meth:`~xarray.DataArray.to_zarr`.
   (:issue:`7692`, :pull:`7693`) .
   By `Joe Hamman <https://github.com/jhamman>`_.
+- Many error messages related to invalid dimensions or coordinates now always show the list of valid dims/coords (:pull:`8079`).
+  By `András Gunyhó <https://github.com/mgunyho>`_.
 
 Breaking changes
 ~~~~~~~~~~~~~~~~