add entity information to the README

README.md

@@ -16,6 +16,23 @@ _BWT Perla integration repository for [HACS](https://github.com/custom-component
 * Setup integration and enter host / ip address and the "Login-Code"
 * Optional: set bwt total output as water source in the energy dashboard
 
+### Entities
+
+| Entity Id(s) | Information |
+| ------------- | ------------- |
+| total_output | Increasing value of the blended water = the total water consumed. Use this as water source on the energy dashboard. |
+| errors, warnings | The fatal errors and non-fatal warnings. Comma separated list or empty if no value present. [List of values](https://github.com/dkarv/bwt_api/blob/main/src/bwt_api/error.py). |
+| state | State of the device. Can be OK, WARNING, ERROR |
+| holiday_mode | If the holiday mode is active (true) or not (false) |
+| holiday_mode_start | Undefined or a timestamp if the holiday mode is set to start in the future |
+| hardness_in, hardness_out | dH value of the incoming and outgoing water. Note that this value is not measured, but configured on the device during setup |
+| customer_service, technician_service | Timestamp of the last service performed by the customer or technician |
+| regenerativ_level | Percentage of salt left |
+| regenerativ_days | Estimated days of salt left |
+| regenerativ_mass | Total grams of salt used since initial device setup |
+| last_regeneration_1, last_regeneration_2 | Last regeneration of column 1 or 2 |
+| counter_regeneration_1, counter_regeneration_2 | Total count of regenerations since initial device setup |
+
 ### Get monthly / daily / hourly / per 15 minute / ... water usage
 
 Unfortunately, the BWT API does not hand out these values. You can setup a _Utility Meter_ in Home Assistant to calculate them: