GH-45644: [Doc][Python] Document timezone-aware NumPy object conversion

Author: alex-anast

docs/source/python/numpy.rst

@@ -101,6 +101,17 @@ If you need to preserve timezone information, there are two alternatives:
      1   2025-01-01 00:00:00+00:00
      dtype: datetime64[s, UTC]
 
+  To convert back to NumPy while preserving timezone information, use
+  ``timestamp_as_object=True`` to get an object array of Python ``datetime``
+  objects:
+
+  .. code-block:: python
+
+     >>> arr.to_pandas(timestamp_as_object=True).to_numpy()  # doctest: +ELLIPSIS
+     array([datetime.datetime(2025, 1, 1, 0, 0, tzinfo=...),
+            datetime.datetime(2025, 1, 1, 0, 0, tzinfo=...)],
+           dtype=object)
+
   .. note::
 
      For nested types (e.g., list arrays containing timestamps),