Better handling of multiple umbrel nodes on the network

[knorrium]

The documentation says that when there are multiple Umbrel instances on the network, they can be accessed through umbrel-2.local, umbrel-3.local etc.

That seems to work fine, but I believe the actual hostname could be updated to prevent collisions and it would also fix the connection instructions in the apps:

Note the address on the nav bar vs the hostname reported by the console:

Core and Electrs instructions:

I'm not sure if this is due to the collision but my latest Umbrel Home node becomes unresponsive after a few days.

[highghlow]

Umbrel apps source the device's hostname through an env variable passed to them, so probably that should be updated to reflect the dns change