Fix more two-arg raise statements.

Doc/tutorial/errors.rst

@@ -216,7 +216,7 @@ Raising Exceptions
 The :keyword:`raise` statement allows the programmer to force a specified
 exception to occur. For example::
 
-   >>> raise NameError, 'HiThere'
+   >>> raise NameError('HiThere')
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
    NameError: HiThere
@@ -231,7 +231,7 @@ handle it, a simpler form of the :keyword:`raise` statement allows you to
 re-raise the exception::
 
    >>> try:
-   ...     raise NameError, 'HiThere'
+   ...     raise NameError('HiThere')
    ... except NameError:
    ...     print('An exception flew by!')
    ...     raise