Added Glances

[mcmikemn]

Added Glances, an open-source system cross-platform monitoring tool. It's like a light version of Prometheus.

I added it because Homepage has a widget for it and I wanted to see basic server stats from Homepage. (Homepage also has a widget for Prometheus, but it's far more basic - it's funny: Promethus is a more robsut metrics monitor but the Homepage widget is basic, Glances is a farily basic metrics monitor but the widget is more robust).

[EnigmaCurry]

https://github.com/nicolargo/glances/tree/24c87253595f9d3168afc26e82cfa464fc7523b9?tab=readme-ov-file#docker-the-cloudy-way

This example does use network mode host, but not privileged. Is privileged necessary?

Nevermind, it matters not because of the bind mounted socket gives them privileged access anyway.

[EnigmaCurry]

## Warning

This container has privileged access to your host, and full control of
Docker via bind mount socket. It also uses the docker flag
`network_mode: host`. This gives unlimited access to your host
network. You should not install this unless you completely trust this
service. To enforce the use of Traefik as your entrypoint, your
external firewall should block TCP ports 61208 and 61209.

[EnigmaCurry]

With the addition of the README warning above, I am happy with this as-is.

[mcmikemn]

I reduced priveleges, added alert, variablized bind mount to docker socket, updated readme.

You were already OK with this PR with only the alert added. Do you want to review my changes, @EnigmaCurry?

[mcmikemn]

Oh wait, I want to make one more change.