datetime.rst: improve combine() docs (#101338)

The explanation on handling of datetime as the date arg was confusingly mixed with an unrelated item, and lacked proper arg name formatting.

Author: belm0

Doc/library/datetime.rst

@@ -982,12 +982,11 @@ Other constructors, all class methods:
  are equal to the given :class:`.time` object's. If the *tzinfo*
  argument is provided, its value is used to set the :attr:`.tzinfo` attribute
  of the result, otherwise the :attr:`~.time.tzinfo` attribute of the *time* argument
- is used.
+ is used. If the *date* argument is a :class:`.datetime` object, its time components
+ and :attr:`.tzinfo` attributes are ignored.
 
  For any :class:`.datetime` object *d*,
- ``d == datetime.combine(d.date(), d.time(), d.tzinfo)``. If date is a
- :class:`.datetime` object, its time components and :attr:`.tzinfo` attributes
- are ignored.
+ ``d == datetime.combine(d.date(), d.time(), d.tzinfo)``.
 
  .. versionchanged:: 3.6
  Added the *tzinfo* argument.