Internal GitHub Pages type solution for private repos and sites

[mfisher87]

Sometimes the business requires private documentation or other private resources. We should have an easy way to do a similar workflow to "Markdown in a repo -> live static site on every commit" for an internal site and private repo, for example a business-specific slide deck or a documentation site about confidential hardware infrastructure.

[mfisher87]

https://docs.meli.charlie-bravo.be/get-started/upload-site