Update tesla_wall_connector.markdown

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 The Tesla Wall Connector integration allows you to integrate your Gen 3 [Tesla Wall Connector](https://www.tesla.com/support/home-charging-installation/wall-connector) with Wi-Fi into Home Assistant.
 
 {% include integrations/config_flow.md %}
+
+## Supported functionality
+
+### Entities
+
+The Tesla Wall Connector integration provides the following entities.
+
+#### Sensors
+- **Energy** - Running total of energy used by the Wall Connector.
+- **Session energy** - Energy used during the current charging session.
+- **Status** - Present status of the Wall Connector.
+  - **Possible states** - booting, not_connected, connected, ready, negotiating, error, charging_finished, waiting_car, charging_reduced, charging
+- **Contactor closed** - Binary sensor indicating if the Wall Connector is currently charging.
+- **Grid frequency** - Sensor for grid frequency of the incoming AC power.
+- **Grid voltage** - Sensor for grid voltage of the incoming AC power.
+- **Handle temperature** - Sensor for temperature of the Wall Connector handle.
+- **MCU temperature** - Sensor for temperature of the Wall Connector Main Computing Unit (MCU).
+- **PCB temperature** - Sensor for temperature of the Wall Connector Power Control Board (PCB).
+- **Phase current** - Sensor for the power current of each incoming AC electricity phase.
+- **Phase voltage** - Sensor for the voltage of each incoming AC electricity phase.
+- **Vehicle connected** - Binary sensor indicating if a vehicle is connected.
+- **Status code** - Sensor for error codes generated by the Wall Connector.
+
+## Energy dashboard
+
+Energy usage can be easily added to the built-in [Energy dashboard](/docs/energy/) using the energy sensor.
+
+To add the Tesla Wall Connector to your Energy dashboard:
+
+1. Navigate to **Settings** > **Dashboards** > **Energy**.
+2. In the **Electricity grid** section, select **Add consumption**.
+3. Select the Tesla Wall Connector's "Energy" sensor.
+4. Select **Save**.