Added documentation for JustNimbus integration (#23702)

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

source/_integrations/justnimbus.markdown

@@ -0,0 +1,43 @@
+---
+title: JustNimbus
+description: Instructions on how to configure the JustNimbus integration within Home Assistant
+ha_category:
+  - Environment
+ha_release: 2022.9
+ha_iot_class: Cloud Polling
+ha_domain: justnimbus
+ha_platforms:
+  - sensor
+ha_config_flow: true
+ha_integration_type: integration
+---
+
+The JustNimbus integration queries the JustNumbus API used by the JustNimbus web dashboard.
+This integration allows you to collect and save data to get an historic overview of your water bag
+usage.
+
+## Prerequisites
+
+To configure and use this integration, you need to have a
+[JustNimbus water bag](https://justnimbus.com/regenwatersysteem/) (Dutch), and
+you need to be subscribed for the web dashboard functionality. For this configuration, you need the
+client ID from the URL. For example: `https://dashboard.justnimbus.com/api/installation/<client_id>/data`.
+
+{% include integrations/config_flow.md %}
+
+## Sensor Types
+
+When configured, the integration will create twelve sensors for each configured client ID:
+
+- Pump flow, in `L/min` (Liters/minute)
+- Drink flow, in `L/min` (Liters/minute)
+- Pump pressure, in `bar`
+- Pump starts, a number counting the number of times the pump has started
+- Pump hours, a number counting the number of hours the pump has been used
+- Reservoir temperature, in `°C`
+- Reservoir content, in `L` (Liters)
+- Total saved, in `L` (Liters)
+- Total replenished, in `L` (Liters)
+- Error code
+- Total use, in `L` (Liters)
+- Max reservoir content, in `L` (Liters)