Documentation needs to be made consistent

[djgroen]

We use ReadTheDocs now, but many documents are still in doc in Markdown, not in docs in .rst format. We should amend this, so that the docs are in one place...

[arabnejad]

after converting Markdown to rst format, should we use separate folder for each category, such as /docs/container/ , /docs/plugins/ and so on, or just convert all .md files to .rst and add into docs folder ?

[djgroen]

Let's make subfolders. I think it is cleaner that way.

[djgroen]

I don't see this happening today, and it's not urgent.