Fix markup

Doc/lib/libdatetime.tex

@@ -569,7 +569,7 @@ Other constructors, all class methods:
 
   \method{fromtimestamp()} may raise \exception{ValueError}, if the
   timestamp is out of the range of values supported by the platform C
-  \cfunction{localtime()} or \cfunction(gmtime()} functions.  It's common
+  \cfunction{localtime()} or \cfunction{gmtime()} functions.  It's common
   for this to be restricted to years in 1970 through 2038.
   Note that on non-POSIX systems that include leap seconds in their
   notion of a timestamp, leap seconds are ignored by