Create page for bt_smarthub device tracker (#6528)

* Create page for bt_smarthub device tracker

* Update device_tracker.bt_smarthub.markdown

* Update device_tracker.bt_smarthub.markdown

* Update device_tracker.bt_smarthub.markdown

* Update device_tracker.bt_smarthub.markdown

* Fix unnecessary blank lines

* Add missing elements

source/_components/device_tracker.bt_smarthub.markdown

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+---
+layout: page
+title: "BT Smart Hub"
+description: "Instructions on how to integrate BT Smart Hub router into Home Assistant."
+date: 2018-10-05 10:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: bt.png
+ha_category: Presence Detection
+ha_release: "0.82"
+ha_iot_class: "Local Polling"
+---
+
+This platform offers presence detection by looking at connected devices to a [BT Smart Hub](https://en.wikipedia.org/wiki/BT_Smart_Hub) based router.
+This router is sometimes referred to as the BT Home Hub 6.
+
+## {% linkable_title Configuration %}
+
+To use a BT Smart Hub router in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+device_tracker:
+  - platform: bt_smarthub
+```
+
+{% configuration %}
+host:
+  description: The IP address of your router 
+  default: 192.168.1.254
+  required: false
+  type: string
+{% endconfiguration %}
+
+See the [device tracker component page](/components/device_tracker/) for instructions on how to configure the people to be tracked.