[Tagging] landcover=trees definition

[Daniel Koć]

I have just discovered that while landcover=trees has no Wiki page, it's 
quite established tag (I wouldn't say "popular" here, because it's just 
about 1% of forest/wood uses) and we could officially define as a 
generic tag for trees areas, when it's not clear for the mapper if it's 
natural or not ("forest" vs "wood").

Do you agree with this idea?

-- 
"The train is always on time / The trick is to be ready to put your bags 
down" [A. Cohen]