Revert description modification for fmod

Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>

Doc/library/math.rst

@@ -273,10 +273,7 @@ Floating point arithmetic
 
 .. function:: fmod(x, y)
 
-   Return the remainder of division ``x / y``,
-   as defined by the platform C library function ``fmod(x, y)``.
-
-   Note that the
+   Return ``fmod(x, y)``, as defined by the platform C library. Note that the
    Python expression ``x % y`` may not return the same result.  The intent of the C
    standard is that ``fmod(x, y)`` be exactly (mathematically; to infinite
    precision) equal to ``x - n*y`` for some integer *n* such that the result has