NB_USE_NETSTACK_MODE not documented

[mitchplze]

The doc page for CLI / and list of environment variables has no entry for NB_USE_NETSTACK_MODE.

There is some information in one example guide here:

NB_USE_NETSTACK_MODE Set to true to enable netstack mode. (Default: false) NB_SOCKS5_LISTENER_PORT: Set the port where the Socks5 proxy listens. (Default: 1080)

And then a little futher down there is more:

[...] Docker containers are not allowed to create new VPN interfaces by default. For that reason, you can run a NetBird agent in a standard mode to enable the netstack mode

docker run --rm --name PEER_NAME --hostname PEER_NAME -d \
-e NB_SETUP_KEY=<SETUP KEY> -e NB_USE_NETSTACK_MODE=true -e  NB_SOCKS5_LISTENER_PORT=1080 -v netbird-client:/var/lib/netbird netbirdio/netbird:latest

This is useful when you want to configure a simple routing peer without adding privileged permissions or linux capabilities.

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This results in even more confusion when you look at my other issue netbirdio/netbird#4624. There are multiple conflicting documentation entries for Docker usage, all across NetBird as a platform.

I think it would be good to have consistent documentation usage covering Docker as both a host, and as a sidecar. Similar to how Tailscale does it.

I would be happy to help out with a NetBird doc re-work, to clarify some of this usage, if I can confirm what it should be and exactly what modes/configurations are supported.