fix True/False/None reST markup

Doc/reference/compound_stmts.rst

 .. _compound:
 
 *******************
 Compound statements
 *******************
 
 .. index:: pair: compound; statement
 
 Compound statements contain (groups of) other statements; they affect or control
 the execution of those other statements in some way.  In general, compound
@@ skipping 354 matching lines @@
       The :keyword:`with` statement guarantees that if the :meth:`__enter__`
       method returns without an error, then :meth:`__exit__` will always be
       called. Thus, if an error occurs during the assignment to the target list,
       it will be treated the same as an error occurring within the suite would
       be. See step 6 below.
 
 #. The suite is executed.
 
 #. The context manager's :meth:`__exit__` method is invoked.  If an exception
    caused the suite to be exited, its type, value, and traceback are passed as
-   arguments to :meth:`__exit__`. Otherwise, three :const:`None` arguments are
+   arguments to :meth:`__exit__`. Otherwise, three ``None`` arguments are
    supplied.
 
    If the suite was exited due to an exception, and the return value from the
    :meth:`__exit__` method was false, the exception is reraised.  If the return
    value was true, the exception is suppressed, and execution continues with the
    statement following the :keyword:`with` statement.
 
    If the suite was exited for any reason other than an exception, the return
    value from :meth:`__exit__` is ignored, and execution proceeds at the normal
    location for the kind of exit that was taken.
@@ skipping 243 matching lines @@
    or the execution of a :keyword:`return`, :keyword:`continue`, or
    :keyword:`break` statement.
 
 .. [#] A string literal appearing as the first statement in the function body is
    transformed into the function's ``__doc__`` attribute and therefore the
    function's :term:`docstring`.
 
 .. [#] A string literal appearing as the first statement in the class body is
    transformed into the namespace's ``__doc__`` item and therefore the class's
    :term:`docstring`.