[Tagging] Clarify tag access doc

[SomeoneElse]

Pieren wrote:
> If you specify the access for "customers", then you have to do it for 
> "employees" or "visitors" as well. Think about parkings or entrances 
> in theatres, hotels, airports, supermarkets, malls, factories, 
> hospitals, etc...

Why?  If I'm mapping a pub car park I want some way to say "access != 
the great unwashed public".  I'm not going to care that the bar staff 
actually tend to park in a particular corner, or around the back.

Cheers,
Andy