Add De Lijn component documentation (#9507)

* Add De Lijn component

Documentation of the De Lijn component to add passages of stops of the Flemish public transport company into home assistant

* ✏️ Tweak

* Update source/_components/delijn.markdown

Suggested corrections applied

Co-Authored-By: Klaas Schoute <klaas_schoute@hotmail.com>

* Some suggested changes added

Sensor added as ha_category.
Only show the mandatory items in the configuration example.
Rewritten the Configuration part a little bit to align with example.
Added some additional information on the Full Configuration to clarify the outcome of that configuration.

* Alignment of configuration names

Aligned the names in the configuration explanation with the actual configuration names.

* Linked to custom lovelace card added

Added link to custom lovelace card that makes best use of all the retrieved features (ie. correct colour codes of the line cards)

* Apply suggestions from code review

Co-Authored-By: Klaas Schoute <klaas_schoute@hotmail.com>
Co-Authored-By: Franck Nijhof <frenck@frenck.nl>

* Documents aligned with changes in component code

sub_key was replaces with api_key in the component code so the reference is changed in the documentation here as well.

* Updated with changes to component

The delijn component has been updated based on feedback given in PR #24265. Based on those changes the documentation had to be updated as well. Now documentation and component are aligned again.

* ✏️ Markdown cleanup

* 🎨 Adds De Lijn logo

source/_components/delijn.markdown

@@ -0,0 +1,73 @@
+---
+title: "De Lijn"
+description: "Instructions on how to integrate De Lijn (Flemish public transport company) departure times into Home Assistant."
+ha_release: 0.97
+ha_category: 
+  - Transport
+  - Sensor
+ha_iot_class: Cloud Polling
+logo: delijn.svg
+---
+
+The `delijn` sensor will give you the departure time of the next bus, tram or subway at a specific stop of the De Lijn public transport network in Flanders (Belgium).
+
+## Setup
+
+Create a developer account at [De Lijn Open Data portal](https://data.delijn.be/) to get a free API subscription key.
+For valid stop IDs check for the 6 digits at the physical stops or visit the [stops page](https://www.delijn.be/en/haltes/) of the De Lijn website.
+
+## Configuration
+
+To enable this sensor, add the following lines to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: delijn
+    api_key: 'API_SUBSCRIPTION_KEY'
+    next_departure:
+    - stop_id: 'STOP_ID'
+```
+
+{% configuration %}
+api_key:
+  description: "API Subscription key needed to access De Lijn API's."
+  required: true
+  type: string
+next_departure:
+  description: One or multiple departure sensors.
+  required: true
+  type: list
+  keys:
+    stop_id:
+      description: "ID of the stop, e.g. `200552`."
+      required: true
+      type: string
+    number_of_departures:
+      description: "Specify the maximum number of departures/passages at a stop to retrieve"
+      required: false
+      default: 5
+      type: integer
+{% endconfiguration %}
+
+## Examples
+
+### Full configuration
+
+The example below shows a full configuration with two sensors, only the abcdefg needs to be replaced with an actual API subscription key. The first stop_id will return the default next 5 passages, the second stop_id has been forced to return the next 20 passages.
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  # De Lijn public transport
+  - platform: delijn
+    api_key: 'abcdefg'
+    next_departure:
+    - stop_id: '200018'
+    - stop_id: '201169'
+      number_of_departures: 20
+```
+
+## Custom Lovelace card
+
+Works best with the following custom Lovelace card: <https://github.com/bollewolle/delijn-card>