Add documentation for hvv_departures (#12002)

Co-authored-by: Franck Nijhof <frenck@frenck.nl>
Co-authored-by: Franck Nijhof <git@frenck.dev>

source/_integrations/hvv_departures.markdown

@@ -0,0 +1,45 @@
+---
+title: HVV Departures
+description: Display the departures of busses, trains and fairies in Hamburg within Home Assistant.
+ha_category:
+  - Transport
+ha_iot_class: Cloud Polling
+ha_release: 0.112
+ha_config_flow: true
+ha_codeowners:
+  - '@vigonotion'
+---
+
+The `hvv_departures` sensor will display the departures of busses, trains and fairies in Hamburg.
+
+## Configuration
+
+Menu: *Configuration* > *Integrations*
+
+Press on **HVV Departures** and configure the integration:
+
+- You can keep the default host (only change it if you know what you are doing)
+- Enter your API credentials (see [How to get the API credentials](#how-to-get-the-api-credentials))
+- Enter your station. You can also enter your address or a point of interest.
+- Select the station/address/poi you want
+
+After that, you will get a sensor showing the time until the next departure.
+
+## Options
+
+Menu: *Configuration* > *Integrations* > *Select your new integration* > *Press the cog in the upper left corner*
+
+- **select lines**: filter the departures on the station to only show departures for the selected lines.
+- **offset**: set this if you want to list the departures some minutes in the future, for example, if you live ten minutes away from the station.
+- **use realtime data**: enable this to include delay and cancellation information.
+
+
+## How to get the API credentials
+
+You have to apply for credentials via the HVV website. You can see their official guide [here](https://www.hvv.de/de/fahrplaene/abruf-fahrplaninfos/datenabruf) (the page is only available in German).
+
+In your mail, tell them you are using your API credentials for use within Home Assistant. They will send you a contract you will have to sign and send back. After about a week, you will receive your API credentials.
+
+## Data
+
+Data is provided by [HVV](https://www.hvv.de/).