Update note on requirements for Huginn statistics

[cameronwp]

Description

Update docs on requirements for Huginn's endpoints. It's required that PUBLIC=1 for odin to pull stats from the server. See this discussion

I didn't test locally, but no code changes were made.

Contributions

• I added docs on requiring PUBLIC=1 to get stats from Huginn because it is an undocumented requirement.

Checklist

• I added one or multiple labels which best describes this PR.
• I have tested the changes locally.
• This PR has a reviewer on it.
• I have validated my changes in a docker container and on Ubuntu. (Only needed for Odin or Docker Changes)

[cameronwp]

To the maintainers: apologies. For the life of me, I can't figure out how to add a label to the PR.