The auto-mode-alist entry for coq-mode and friends are already added by proof-general's autoloads file, and neither coq-mode nor company-coq-mode belong to proof-site specifically, so they shouldn't be treated like they are (this could cause autoloading errors).
The `def-package!` block altogether is unnecessary. The only thing we need is to enable `company-coq-mode` on coq-mode-hook. However, having a one-line config.el is a tad excessive, so we put it in autoload.el instead.
