[Development] ChangeLog updated for 5.2.0

[Oswald Buddenhagen]

On Mon, Nov 25, 2013 at 11:31:07AM -0800, Thiago Macieira wrote:
> On segunda-feira, 25 de novembro de 2013 19:47:24, Marc Mutz wrote:
> > I don't see a contradiction to what I was proposing: -1 if task-number is 
> > present, too, otherwise just warn.
> 
> Warn if a task-number is present, no message otherwise.
>
define "warn". i would favor a hint without negative rating.