[Tagging] tagging single trees

[lkytomaa at cc.hut.fi]

> That is not true. There already is an extension tag, denotation=avenue or
> denotation=urban and some people have used it when mass-mapping generic

Glad that somebody documented it properly in the Wiki right
from the start. Oh bummer, nobody did.

It was mentioned, but not documented, on the project of the
week page about adding trees, but even there only after the
week was already over. Every tree deserves additional tags,
just add data.

--
Alv