Add Garages Amsterdam Integration (#15629)

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

source/_integrations/garages_amsterdam.markdown

@@ -0,0 +1,36 @@
+---
+title: Garages Amsterdam
+description: Instructions on how to integrate Garages Amsterdam within Home Assistant.
+ha_category:
+  - Sensor
+  - Binary Sensor
+ha_release: 2021.6
+ha_codeowners:
+  - '@klaasnicolaas'
+ha_config_flow: true
+ha_iot_class: Cloud Polling
+ha_domain: garages_amsterdam
+---
+
+The Garages Amsterdam integration uses an API provided by the municipality of Amsterdam, to measure the occupancy of Amsterdam parking garages in the Netherlands. You can track multiple garages by adding the integration multiple times.
+
+{% include integrations/config_flow.md %}
+
+### Sensor
+
+When you add a parking garage, 4 sensors are created in your configuration by default:
+
+- **Free space long** - Number of free parking spaces for cardholders or reserved spaces
+- **Free space short** - Number of free parking spaces for regular paid parking
+- **Long capacity** - Total of parking spaces for cardholders or reserved spaces
+- **Short capacity** - Total of parking spaces for regular paid parking
+
+<div class='note warning'>
+
+  Some parking garages don't have long-term parking spaces, in which case the 2 specific **Long** sensors will not be created.
+
+</div>
+
+### Binary Sensor
+
+Each parking garage also has a binary sensor, which indicates whether there are problems in the data provision from the API. When it indicates `ok` everything is fine. If the state changes to `problem`, the upstream data might not be up to date or reliable and will remain in this state until new data is coming in.