fix markup error

Doc/whatsnew/whatsnew24.tex

@@ -317,7 +317,7 @@ compatibility with whatever syntax is used in 2.4final.
 \seepep{318}{Decorators for Functions, Methods and Classes}{Written 
 by Kevin D. Smith, Jim Jewett, and Skip Montanaro.  Several people
 wrote patches implementing function decorators, but the one that was
-actually checked in was patch #979728, written by Mark Russell.}
+actually checked in was patch \#979728, written by Mark Russell.}
 \end{seealso}
 
 %======================================================================