[Tagging] Fire_hydrant: tagging namespace documentation

[Moritz]

Am 2017-09-12 23:16, schrieb Viking:
> I've found that in man_made=water_well [0], pump=* and pump:type=* are
> already in use. I think we can use the same tags for hydrants
> connected to fire water wells. Don't we?
> 

+1

If we add new values like bilge_pump and electric_pump to the pump:type 
key.

Moritz