add clarifying warning to vhost config.
add clarifying warning to vhost config.

DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,alkadis/vcv,liqd/adhocracy,phihag/adhocracy,phihag/adhocracy,phihag/adhocracy,liqd/adhocracy,alkadis/vcv,alkadis/vcv,alkadis/vcv,phihag/adhocracy,liqd/adhocracy,liqd/adhocracy,DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,alkadis/vcv,phihag/adhocracy