Guide: Improve Facial Detection

[1-tempest]

This is @mertalev's work from a discord discussion wrapped in an install script, it improves the algorithm for detecting faces.

I just wrapped it in a quick install script to make my life easier building and destroying containers while testing some things.

Figured I'd share it as the work has already been done.

https://github.com/1-tempest/immich-better-face-detection