Fix typo in re.escape documentation (GH-14722)

(cherry picked from commit fb6c1f8)

Co-authored-by: Robert DiPietro <rdipietro@gmail.com>

Author: miss-islington

Doc/library/re.rst

@@ -936,7 +936,7 @@ form.
       >>> print('|'.join(map(re.escape, sorted(operators, reverse=True))))
       /|\-|\+|\*\*|\*
 
-   This functions must not be used for the replacement string in :func:`sub`
+   This function must not be used for the replacement string in :func:`sub`
    and :func:`subn`, only backslashes should be escaped.  For example::
 
       >>> digits_re = r'\d+'