iBeacon-txpower

[DigiH]

Changing the iBeacon decoder power to the more appropriate txpower, in line with other devices already reporting and Decoder registering their txpower, and for distinction between actual Watt Power of the iNode decoder for example,. Additional clarification of its @ 1 m implementation in the unit name and docs.

Checklist:

• The pull request is done against the latest development branch
• Only one feature/fix was added per PR and the code change compiles without warnings
• I accept the DCO.

[1technophile]

Thanks !