convert to mkdocs with auto-publish

[Tieske]

This adds a mkdocs workflow and makes it render a website based on the markdown documentation.

To see what it looks like see https://tieske.github.io/homie5-device-profiles/

The workflow will automatically update the site on each push to main. This is my first try with mkdocs but so far I'm loving the simplicity.

[schaze]

@Tieske I am pulling out of this.

My initial goal was to add JSON as a device description to get rid of all the thousands of subscribes and publishes and also officially add json as a data format, then take over my already 90% finished profiles and optimize them a bit.

At this point this all so far from what I already had done for my homecontrol profiles and what I initially intended for homie that I don't think it makes sense for me to be involved any more.

[Tieske]

I also don't like the overall result so far. I do like the strictness of the profiles I wrote, to be completely identical across implementations. But the massive wall of text it became and the number of rules and relations are too complicated.

[Tieske]

@Thalhammer wdyt?