Question: So I just got ability to edit community wiki but I have no idea what that is.
Also answers do not tell me what is it, where is it, what is looks like?

Yes I've read answers like this:
[What are "Community Wiki" posts?](https://meta.stackexchange.com/questions/11740/what-are-community-wiki-posts)

But it gives no examples of what the things looks like.

Answer: 
The question you linked, and all its answers, are community wiki. Notice how, in the bottom-right where the author's usercard would normally be, it says "community wiki." Below that, you'll find information like the number of revisions.

This is a usercard from a normal Super User post by me:

[![normal](https://i.stack.imgur.com/3e7Tp.png)](https://i.stack.imgur.com/3e7Tp.png)

And this is one from a wiki post mostly written by me:

[![community wiki](https://i.stack.imgur.com/tWF1e.png)](https://i.stack.imgur.com/tWF1e.png)

Note that the links to the user for some community wiki posts here on MSE might not go to the user page, likely because of [the MSO/MSE split](https://meta.stackexchange.com/q/212631/295684).
As already said by Ben, the post you linked is a community wiki.

If you look for more examples, you can use the search option `wiki:yes`. It will give you [all community wiki questions and answers](https://meta.stackexchange.com/search?q=wiki%3Ayes).

I have also [edited](https://meta.stackexchange.com/revisions/11741/52) the community wiki you referenced to include the identification method.