ci: add workflow to convert README to vimdoc

[mikesmithgh]

👋 I created a Github workflow to run panvimdoc on every push that modifies README.md. I tweaked some formatting in the README to allow it to generate correctly.

You may have to enable read and write access to your github actions to allow the bot to commit changes. See setting-the-permissions-of-the-github_token-for-your-repository

Let me know what you think! #hacktoberfest 🎉

It can also be ran locally via:

./panvimdoc.sh --project-name hardtime.nvim  --input-file "../hardtime.nvim/README.md" --vim-version "NVIM v0.7+" --toc true --demojify true --dedup-subheadings false

[m4xshen]

Thanks a lot! I didn't even know that this tool exists.

[mikesmithgh]

Glad to help 🙂