gh-106318: Resolve conflict on str.isalpha() doc

Author: adorilson

Doc/library/stdtypes.rst

@@ -1990,9 +1990,9 @@ expression support in the :mod:`re` module).
    from the `Alphabetic property defined in the section 4.10 'Letters, Alphabetic, and
    Ideographic' of the Unicode Standard
    <https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-4/#G91002>`_.
-   For example::
+   For example:
 
-   ..doctest::
+   .. doctest::
 
       >>> 'a commom word'.isalpha()
       False