Add Shodan sensor docs (#3156)

source/_components/sensor.shodan.markdown

@@ -0,0 +1,36 @@
+---
+layout: page
+title: "Shodan Sensor"
+description: "Instructions how to integrate Shodan sensors into Home Assistant."
+date: 2017-08-09 10:30
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category: Sensor
+ha_iot_class: "Cloud Polling"
+logo: shodan.png
+ha_release: 0.51
+---
+
+
+The `shodan` sensor platform is displaying the total of result of a [Shodan](https://pi-hole.net/) query.
+
+Use "Show API Key" in the upper right corner when you are logged in or got to your "My Account" page to retrieve your API key.
+
+To enable this sensor, add the following lines to your `configuration.yaml` file for a GET request:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: shodan
+    api_key: SHODAN_API_KEY
+    query: 'home-assistant'
+```
+
+Configuration variables:
+
+- **api_key** (*Required*): The API key for Shodan.io.
+- **query** (*Required*): The search string.
+- **name** (*Optional*): Name of the Shodan sensor.
+