lovelace

Add install/usage instructions for non yaml mode users.

Describe the solution you'd like
Combine both entity_id and attribute, so we could get (and transform) something from an entity where the primary attribute is not what we want, without creating a new sensor.

ie:

   - entity_id: sensor.deebot920_last_cleaning
     attribute: timestamp
     value_template: '{{ value | timestamp_custom("%Y/%m/%d %H:%M:%S") }}'
     subtitle: Last job

I know this would seem obvious to someone already using a thermostat, but for someone who is starting with this card to set up their first thermostat, it would be nice to suggest setting up the generic_thermostat in configuration.yaml.

Cheers, Richard