gh-106318: Add doctest role for str.strip() method

Author: adorilson

Doc/library/stdtypes.rst

@@ -2777,7 +2777,11 @@ expression support in the :mod:`re` module).
    The *chars* argument is a string specifying the set of characters to be removed.
    If omitted or ``None``, the *chars* argument defaults to removing whitespace.
    The *chars* argument is not a prefix or suffix; rather, all combinations of its
-   values are stripped::
+   values are stripped.
+
+   For example:
+
+   .. doctest::
 
       >>> '   spacious   '.strip()
       'spacious'
@@ -2788,7 +2792,10 @@ expression support in the :mod:`re` module).
    from the string. Characters are removed from the leading end until
    reaching a string character that is not contained in the set of
    characters in *chars*. A similar action takes place on the trailing end.
-   For example::
+
+   For example:
+
+   .. doctest::
 
       >>> comment_string = '#....... Section 3.2.1 Issue #32 .......'
       >>> comment_string.strip('.#! ')