gh-106318: Add examples for str.ljust() method

Author: adorilson

Doc/library/stdtypes.rst

@@ -2261,12 +2261,16 @@ expression support in the :mod:`re` module).
    done using the specified *fillchar* (default is an ASCII space). The
    original string is returned if *width* is less than or equal to ``len(s)``.
 
-   For example::
+   For example:
+
+   .. doctest::
 
       >>> 'Python'.ljust(10)
       'Python    '
       >>> 'Python'.ljust(10, '.')
       'Python....'
+      >>> 'Monty Python'.ljust(10, '.')
+      'Monty Python'
 
    See also :meth:`rjust`.