[Tagging] Tagging Free Water for cafés, bars, restaurant

[Joseph Eisenberg]

free_water_table= or free_water:table= will be confusing for places
that sell take-out food and don't have tables, for examples small
fast-food restaurants, convenience shops, etc.

The word "customers" should be included, since what you are trying to
specify is that "you can only get free water if you buy something
else", and "customers" is the standard term in Openstreetmap for this
idea.

- Joseph Eisenberg