Add Sample websites that used Dokka to generate their docs

[kuyazee]

A good example of this is how realm's jazzy has examples of a few websites that used their tool to generate documentation.

[RaymondChan1]

I think this is a good idea, I was searching for sample output a while ago.

[kuyazee]

@RaymondChan1 Add a 👍🏻+1 reaction to the issue, for it to get the traction it needs.

[CommanderTvis]

Here are two working Dokka generated sites set up by me:
https://mipt-npm.github.io/kmath/
http://cmdr_tvis.gitlab.io/plugin-api/

Another nice example is the kotlinx-coroutines documentation site:
https://kotlin.github.io/kotlinx.coroutines/