Documentation for kwb component (#2209)

* Create sensor.kwb.markdown

* Layout changes

* Added variable documentation

Also, here's a nice KWB logo: http://www.schneider-haustechnik.at/images/logo_kwb.png

* Update sensor.kwb.markdown

Changed ordering and fixed some formatting.

* Update sensor.kwb.markdown

Spelling

source/_components/sensor.kwb.markdown

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+---
+layout: page
+title: "KWB Easyfire Sensor"
+description: "Instructions how to integrate the KWB Easyfire sensor into Home Assistant."
+date: 2017-03-06 14:10
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: home-assistant.png
+ha_category: Sensor
+ha_iot_class: "Local Polling"
+ha_release: 0.40
+---
+
+The `kwb` component integrates the sensors of KWB Easyfire pellet central heating units with the Comfort3 controller (http://www.kwbheizung.de/de/produkte/kwb-comfort-3.html) into Home Assistant.
+
+Direct connection via serial (RS485) or via telnet terminal server is supported. The serial cable has to be attached to the control unit port 25 (which is normally used for detached control terminals).
+
+Since this serial protocol is proprietary and closed, only most temperature sensors and a few control relays are supported, the rest is still WIP (see https://www.mikrocontroller.net/topic/274137).
+
+Direct connection via serial port:
+```yaml
+# Example configuration.yaml entry
+- platform: kwb
+    name: kwb
+    device: "/dev/ttyUSB0"
+    type: serial
+    raw: False
+```
+
+Telnet terminal server with a serial-ethernet converter:
+```yaml
+# Example configuration.yaml entry
+  - platform: kwb
+    name: kwb
+    host: <ip>
+    port: 23
+    type: tcp
+    raw: False
+```
+
+Configuration variables:
+
+*Required if used with a serial-ethernet converter*
+
+- **host**: The IP-address of the serial server
+- **port**: The TCP-port of the serial server
+- **type**: tcp
+
+*Required if used directly with a serial port*
+
+- **device**: The serial device of the machine
+- **type**: serial
+
+*Optional for both cases*
+
+- **name**: The name of the device used in the frontend
+- **raw**: Should the raw serial output be shown as a sensor