Make Repeating status check attempts configurable

[ocarlsen]

When starting up the image, it says

"Repeating status check attempts another 14 times"

I would like to make this configurable.

[Voyz]

Set IBEAM_MAX_STATUS_CHECK_RETRIES environment variable to modify the amount of times it retries.

Thanks for pointing it out, the documentation is out of date. I'll sit down to update it once I find a minute 🙏

See https://github.com/Voyz/ibeam/blob/master/ibeam/src/var.py for a most recent list of supported environment variables.