actually tell the name of the flag to use

Doc/library/2to3.rst

@@ -42,7 +42,7 @@ original is also be made.)  Writing the changes back is enabled with the
 
    $ 2to3 -w example.py
 
-After transformation :file:`example.py` looks like this::
+After transformation, :file:`example.py` looks like this::
 
    def greet(name):
        print("Hello, {0}!".format(name))
@@ -79,12 +79,12 @@ flag.  Note that *only* doctests will be refactored.
 The :option:`-v` option enables the output of more information on the
 translation process.
 
-2to3 can also treat ``print`` as a function instead of a statement in the
-grammar.  This is useful when ``from __future__ import print_function`` is being
-used.  If this option is not given, the print fixer will surround print calls in
-an extra set of parentheses because it cannot differentiate between the and
-print statement with parentheses (such as ``print ("a" + "b" + "c")``) and a
-true function call.
+When the :option:`-p` is passed to it, 2to3 treats ``print`` as a function
+instead of a statement.  This is useful when ``from __future__ import
+print_function`` is being used.  If this option is not given, the print fixer
+will surround print calls in an extra set of parentheses because it cannot
+differentiate between the and print statement with parentheses (such as ``print
+("a" + "b" + "c")``) and a true function call.
 
 
 :mod:`lib2to3` - 2to3's library