Add documentation for netatmo public component (#5893)

* Add documentation for netatmo public component

* ✏️ Minor typo

* Use configuration block instead of plain text

* Change version and clarify that sensor is rain-only

* 🔥 Removes duplicate configuration variables header

* ✏️ Tweaks

* Update 'ha_releases'

source/_components/sensor.netatmo_public.markdown

@@ -0,0 +1,67 @@
+---
+layout: page
+title: "Netatmo Public"
+description: "Instructions on how to add sensors using Netatmo public data to Home Assistant."
+date: 2018-07-22 21:18
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: netatmo.png
+ha_category: Sensor
+ha_iot_class: "Cloud Polling"
+ha_release: 0.77
+---
+
+The `netatmo_public` sensor allows you to expose data from [Netatmo](https://weathermap.netatmo.com/) to Home Assistant, even if you don't have a Netatmo device yourself. Currently, only live rain data is supported.
+
+To enable the Netatmo sensor, you have to set up [netatmo](/components/netatmo/).
+
+## {% linkable_title Configuration %}
+
+Next, enable the sensor by adding the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: netatmo_public
+    areas:
+      - lat_ne: 40.719
+        lon_ne: -73.735
+        lat_sw: 40.552
+        lon_sw: -74.105
+```
+
+{% configuration %}
+areas:
+  description: The list contains one or more areas to add as sensors.
+  required: true
+  type: map
+  keys:
+    lat_ne:
+      description: Latitude of north-eastern corner of area.
+      required: true
+      type: string
+    lon_ne:
+      description: Longitude of north-eastern corner of area.
+      required: true
+      type: string
+    lat_sw:
+      description: Latitude of south-western corner of area.
+      required: true
+      type: string
+    lon_sw:
+      description: Longitude of south-western corner of area.
+      required: true
+      type: string
+    name:
+      description: Name of the sensor.
+      required: false
+      type: string
+      default: Netatmo Public Data
+    type:
+      description: How to calculate the value of the sensor if there are multiple stations reporting data. Accepts `max` or `avg`.
+      required: false
+      type: string
+      default: max
+{% endconfiguration %}