gh-127303: Add docs for token.EXACT_TOKEN_TYPES (#127304)

---------

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Tomas R. <tomas.roun8@gmail.com>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Tools/build/generate_token.py

@@ -226,7 +226,8 @@ token_py_template = f'''\
 # {AUTO_GENERATED_BY_SCRIPT}
 '''
 token_py_template += '''
-__all__ = ['tok_name', 'ISTERMINAL', 'ISNONTERMINAL', 'ISEOF']
+__all__ = ['tok_name', 'ISTERMINAL', 'ISNONTERMINAL', 'ISEOF',
+           'EXACT_TOKEN_TYPES']
 
 %s
 N_TOKENS = %d