Update docs/sphinx/source/whatsnew/v0.15.3.rst

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

Author: markcampanelli

docs/sphinx/source/whatsnew/v0.15.3.rst

@@ -16,7 +16,7 @@ Bug fixes
 ~~~~~~~~~
 * Fix :py:func:`pvlib.irradiance.perez` to return 0 when both DHI and
   DNI are zero. (:issue:`2801`, :pull:`2808`)
-* Fix :py:func:`pvlib.irradiance.perez` to not return zero (instead NaN) when
+* Fix :py:func:`pvlib.irradiance.perez` to return NaN when
   airmass is NaN and either DHI or DNI are NaN. (:issue:`2801`, :pull:`2808`)
 
 Enhancements