add integration kraken (#11891)

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

source/_integrations/kraken.markdown

@@ -0,0 +1,30 @@
+---
+title: Kraken
+description: Instructions on how to integrate Kraken.com sensors into Home Assistant.
+ha_category:
+  - Finance
+  - Sensor
+ha_iot_class: Cloud Polling
+ha_release: 2021.7
+ha_config_flow: true
+ha_quality_scale: gold
+ha_codeowners:
+  - '@eifinger'
+ha_domain: kraken
+ha_platforms:
+  - sensor
+---
+
+The Kraken integration allows you to monitor exchange rates on [kraken.com](https://www.kraken.com/).
+For a list of tradable asset pairs check this [this kraken support article](https://support.kraken.com/hc/en-us/articles/201893658-Currency-pairs-available-for-trading-on-Kraken).
+
+{% include integrations/config_flow.md %}
+
+{% include integrations/option_flow.md %}
+
+{% configuration_basic %}
+Update interval:
+  description: "Seconds between updates"
+Tracked Asset Pairs:
+  description: "Select the assets you want to track. This list is automatically updated with a list of tradable assets on kraken.com"
+{% endconfiguration_basic %}