Article keywords list: filter out section tags

In this PR, we make sure we don't link to section tags (eg `uk/uk` or `world/world`).

Meaning we can turn the article keywords switch back on.

Thanks @gklopper!

![ ](http://s2.developerslife.ru/public/images/gifs/1472c79b-f58f-4ec4-ac19-10cf59152b87.gif)