[3.13] gh-84291: Clarify Pool.imap documentation (GH-155030) (GH-157273)

(cherry picked from commit becf997)

Co-authored-by: Taeknology <20297177+Taeknology@users.noreply.github.com>

Author: miss-islington

Doc/library/multiprocessing.rst

@@ -2450,7 +2450,7 @@ with the :class:`Pool` class.
 
    .. method:: imap(func, iterable[, chunksize])
 
-      A lazier version of :meth:`.map`.
+      An iterator-based version of :meth:`.map`.
 
       The *chunksize* argument is the same as the one used by the :meth:`.map`
       method.  For very long iterables using a large value for *chunksize* can