Document the Fly log shipper

[jsierles]

This includes:

• Moving the README to our site
• Linking the repo back to our site (what we want to do with ALL repos)

Also, these docs should specify how to run the shipper directly from a the Docker image, without having to setup a fly.toml or clone the repo.

[catflydotio]

Have this now: https://fly.io/docs/going-to-production/monitoring/exporting-logs/#the-fly-log-shipper

[andie787]

This is done https://fly.io/docs/metrics-and-logs/exporting-logs/