bug#9432: 24.0.50; doc string of `next-error-highlight'

[Drew Adams]

> > The doc string should say that the fringe indication is 
> > moved when some other locus replaces it - just as it says
> > this for a value of `t'.
> 
> Is this better?
> 
> +If `fringe-arrow', indicate the locus by the fringe arrow
> +indefinitely until some other locus replaces it."

Yes, thanks.

(And FWIW I still think we should also have a value `until-move' that does the
same thing - stay until some other locus replaces it - but using highlighting
instead of fringe.  I've been using that for years myself, so I obviously prefer
it - I generally don't show the fringe.)