Add whats new for dataset interpolation with non-numerics (#5297)

Author: Illviljan

doc/whats-new.rst

@@ -21,7 +21,9 @@ v0.18.1 (unreleased)
 
 New Features
 ~~~~~~~~~~~~
-
+- :py:meth:`Dataset.interp` now allows interpolation with non-numerical datatypes,
+  such as booleans, instead of dropping them. (:issue:`4761` :pull:`5008`).
+  By `Jimmy Westling <https://github.com/illviljan>`_.
 
 Breaking changes
 ~~~~~~~~~~~~~~~~