Warn about barrier=yes

[skyper]

As result of #10622 we now need a warning about barrier=yes as the differences between specific values and simply yes are no longer visible. I already did mention this:

Replying to skyper:

I do not like this change and we need a validator warning about barrier=yes, now, like,

"barrier=yes is unspecific, please replace yes with a specific value".

Some notes:

• the value was added to the wiki without discussion just six month ​ago
• there exists no own wiki page
• if your aerial images are that bad, you can hardly determine barriers at all and definitely miss many entrances.

I did use barrier=yes myself, in the beginning of my tagging, adding it to waterways and other primary features but meanwhile stop doing it as the information is mostly covered with the primary tag.

[mkoniecz]

Good idea, I forgot to report it together with #10622.

[Klumbumbus]

In 7647/josm:

fix #10661 (see #10622) - add warning for barrier=yes (based on text by skyper); typos