Update moving node instructions

[ipopescu]

Updates needed here for 1.5: https://docs.casper.network/operators/maintenance/moving-node/

We need to make sure this moving guide includes moving the unit_files at the DB level. This is new with 1.5 and allows moving with nearly zero rewards loss.
These are located in /var/lib/casper/casper-node/[network name]/unit_files.

They would use rsync and the command depends on how they use ssh to get into the node. Those that are running operators should know how to do this.
Stop validator.
rsync unit_files to running backup
Stop backup
Swap keys to validator on backup
Start backup (new validator)
Swap keys to backup on validator
Start validator (new backup)

Slack info here.

[ipopescu]

Moving this to next sprint since the tech reviewer is OOO.