Remove markdown handling from the docs

Created by: Zaharid

Having markdown required more tooling and more documentation and it is not worth it as it ends up being full of eval_rst clauses.

Convert the existing files to markdown and remove the tooling for it.

One problem is that rst has for some reason no obvious way of having markup inside the links, which is something markdown doesn't know about and needs to be cleaned by hand. Also we had explicit references to markdown source files in varios places. Overall there is quite a big chance of things being missed or getting ugly, even though I tried to remove mos of the warnings.