Adding OTP readme

README.md

@@ -73,6 +73,22 @@ Please let me know if your car works with this addon so I can expand the list!<b
 
 NOTE: Energy status currently available only for cars in the Europe / Middle East / Africa regions. [source](https://developer.volvocars.com/apis/energy/v1/overview/#availability)
 
+## OTP Authentication
+
+As of version <b>v1.9.0</b>, this addon uses the same OTP authentication as the Volvo app. 
+The following steps are required for authentication in exactly this order:
+
+1. Setup volvo2Mqtt, either via Docker, or via HA addon (take a look at the "Setup" section below)
+2. Fill in your settings and start volvo2Mqtt
+3. Your log will show the following lines <br> 
+```Waiting for otp code... Please check your mailbox and post your otp code to the following mqtt topic "volvoAAOS2mqtt/otp_code". Retry 0/15```<br>
+```Waiting for otp code... Please check your mailbox and post your otp code to the following mqtt topic "volvoAAOS2mqtt/otp_code". Retry 1/15```<br>
+```etc ...```
+4. Now, open your mailbox and copy your OTP Code
+5. Open HomeAssistant and search for the entity ID ```text.volvo_otp```
+6. Paste your OTP into the text entity and press Enter
+7. If everything has worked, your addon is now authenticated. In the future, OTP authentication only needs to be done when updating, not when restarting the container.
+
 ## Setup
 <b>Docker:</b>
 
@@ -106,7 +122,6 @@ Here is what every option means:
 | `TZ`                      | `string`  |                                       | **required** | Container timezone eg "Europe/Berlin" from [here](https://docs.diladele.com/docker/timezones.html)|
 
 
-
 [aarch64-shield]: https://img.shields.io/badge/aarch64-yes-green.svg
 [amd64-shield]: https://img.shields.io/badge/amd64-yes-green.svg
 [armhf-shield]: https://img.shields.io/badge/armhf-yes-green.svg