[Tagging] Clarify tag access doc

[Martin Vonwald]

2012/9/13 Janko Mihelić <janjko at gmail.com>:
> I think all those designated/official/yes are the same thing. They allow
> something to go through a certain way. What is different is the source of
> that allowance. If the source is law (access=yes, access:source=de:law) then
> it's official. If you have a "access:source=sign", then it's designated. If
> you don't have a source, then it's just "yes, you can pass here, don't ask
> me how I know".

This makes a lot of sense to me. However I doubt that we are able to
reduce the number of possible access-values: I expect too much
opposition.

Martin