docs: fix formatting and errors

[matheo]

Please read and mark the following check list before creating a pull request:

• I read and followed the CONTRIBUTING.md guide.

Short description of what this resolves:

I found some errors in the documentation with "invisible code" in the quotes,
markdown links that doesn't work inside HTML, indent inconsistencies,
and a couple typos so I took the time to review all the files.

Thanks a lot for the great stuff.