Communicate switch from devmode

[erasmus]

When the Concordium Ledger app is no longer developer-mode only, users will (may?) have to take some steps in order to migrate to the "normal" Ledger app version.

Todo:

1. Figure the exact steps a Ledger users would have to do
2. Write public documentation on the process
3. Optional: reach out to nodes or other key entities to ensure they are aware of the process

[pablozsc]

#1310