Proofreading is something you want to-do quickly and on the fly. If you have docker installed you can download the entire redpen server.
docker pull dai0304/techdoc-redpen
Of course, you're not interested in running a server. You just want to proof read your document.
Bind this alias in your terminal:
alias docker-redpen='docker run -v $(pwd):/redpen -w /redpen --rm -it dai0304/techdoc-redpen'
Start a new terminal and go to your document directory.
Now type docker-redpen.
Your work directory is mounted into the container. And you are in the shared volume directory.
Proof read your file:
redpen mydoc.md
Apart from internal redpen information, you should get remarks on your text. Unless everything is perfect.
Redpen can read all kinds of formats. Personally I use it on my markdown documentation.