Formatting fixes, ocamlformat and makefile

[wmuth]

This PR makes a couple formatting-related fixes:

1. Fixes the markdown file to do what the documentation says it does. dune fmt is a shortcut for dune build @fmt --auto-promote and therefore currently make lint and make fix do the same thing. See the docs.
2. Runs ocamlformat to make sure the files are actually formatted as they should be and adds that commit to the git blame ignore so that the autoformatting run does not show up in git blame.