Fix markdown syntax, minor edits

Ok I fixed the markdown. It's now perfectly visible. I simply used a GitHub-specific markdown feature that allows embedding inline code using triple ```````, the stuff inside of that is not parsed.
I also changed the section structure so that now we have three main sections:
- Setup guides, which contains the installation guides and the guides on how to get stuff working
- Kernel, which contains all the kernel stuff (except the serial console, which I think belongs to the setup guides, as it's pretty important in order to be able to control the newly booted system)
- Initramfs

I should probably split the setup guides into Installation (containing only the first steps to get the chroot and boot it using the different methods) and another section named "Getting stuff working" or something like that where I'll put the wifi, console, etc stuff.