Documentation: Adds deployment instructions for Apache2 as reverse proxy

[nbareil]

Hello team,

This PR provides a configuration example for Apache2 serving as a reverse-proxy to voilà.

I scratched my head for a whole day before figuring the answer so I thought it would be worth adding it to upstream documentation.

While Googling for help, I found no answers, I only found unanswered questions on StackOverflow so I was not alone having a hard time:

• https://stackoverflow.com/questions/77157469/how-to-reverse-proxy-a-voila-server-with-apache
• https://stackoverflow.com/questions/69224610/using-voila-with-jupyter-notebook-proxied-on-apache-server

Hope it helps others!

[github-actions[bot]]

:point_left: Launch a Binder on branch nbareil/voila/main

[trungleduc]

Thanks!