[3.13] pythongh-106318: Add examples for str.rpartition() method (pythonGH-143891) (python#144041)

pythongh-106318: Add examples for str.rpartition() method (pythonGH-143891)
(cherry picked from commit 3c9c3d3)

Co-authored-by: Adorilson Bezerra <adorilson@gmail.com>

Author: miss-islington

Doc/library/stdtypes.rst

@@ -2321,6 +2321,19 @@ expression support in the :mod:`re` module).
    after the separator.  If the separator is not found, return a 3-tuple containing
    two empty strings, followed by the string itself.
 
+   For example:
+
+   .. doctest::
+
+      >>> 'Monty Python'.rpartition(' ')
+      ('Monty', ' ', 'Python')
+      >>> "Monty Python's Flying Circus".rpartition(' ')
+      ("Monty Python's Flying", ' ', 'Circus')
+      >>> 'Monty Python'.rpartition('-')
+      ('', '', 'Monty Python')
+
+   See also :meth:`partition`.
+
 
 .. method:: str.rsplit(sep=None, maxsplit=-1)