Remove outdated statement from math about C standard

Author: hugovk

Doc/library/math.rst

@@ -10,9 +10,6 @@
 
 --------------
 
-This module provides access to the mathematical functions defined by the C
-standard.
-
 These functions cannot be used with complex numbers; use the functions of the
 same name from the :mod:`cmath` module if you require support for complex
 numbers.  The distinction between functions which support complex numbers and