Update README.md

Add new remaining_solar attribute

README.md

@@ -154,6 +154,7 @@ See the [WIKI](https://github.com/slipx06/sunsynk-power-flow-card/wiki/Sensor-Ma
 |grid_status_194: | **Required** | `binary_sensor.grid_connected_status` | Grid Connected Status `on/off` or `1/0` |
 |inverter_status_59: | **Required** | `sensor.overall_state` | Inverter Status `0, 1, 2, 3, 4` or `standby, selftest, normal, alarm, fault` |
 |aux_power_166: | Optional | `sensor.aux_output_power` | Auxilary Power (W) |
+|remaining_solar: | Optional | `sensor.solcast_forecast_remaining_today`| The remaining solar forecast for the day (kWh) |
 
 The card calculates the sensors below based on supplied attributes in the config so you dont need to define them in Home Assistant