Add docs for NUT sensor (#1488)

* Add docs for NUT sensor

* Simplify configuration.yaml example

* Address comments

source/_components/sensor.nut.markdown

@@ -0,0 +1,95 @@
+---
+layout: page
+title: NUT Sensor
+description: "Instructions on how to set up NUT sensors within Home Assistant."
+date: 2016-11-23
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: nut.png
+ha_category: Sensor
+ha_version: 0.34
+---
+
+The `nut` sensor platform allows you to monitor a UPS (battery backup) by using data from a [NUT](http://networkupstools.org/) (Network UPS Tools) server.
+
+To use this sensor platform, you need to add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: nut
+    resources:
+      - ups.load
+      - ups.realpower.nominal
+      - input.voltage
+      - battery.runtime
+```
+
+Configuration variables:
+
+- **name** (*Optional*): Name prefix for defined sensors. Defaults to 'NUT UPS'.
+- **host** (*Optional*): The host name or address of the device that is running NUT. Defaults to localhost.
+- **port** (*Optional*): The port number. Defaults to 3493.
+- **alias** (*Optional*): Name of the ups on the NUT server. Will default to the first UPS name listed.
+- **username** (*Optional*): Username to login to the NUT server. Default is none.
+- **password** (*Optional*): Password to login to the NUT server. Default is none.
+- **resources** array (*Required*): Contains all entries to display.
+
+### {% linkable_title Example  %}
+
+Given the following example output from NUT (Your variables may differ):
+
+```yaml
+'ups.timer.reboot': '0', 
+'battery.voltage': '27.0', 
+'ups.firmware.aux': 'L3 -P ', 
+'ups.mfr': 'American Power Conversion', 
+'battery.runtime.low': '120', 
+'ups.delay.shutdown': '20', 
+'ups.load': '19', 
+'ups.realpower.nominal': '600', 
+'battery.charge.warning': '50', 
+'battery.charge.low': '10', 
+'ups.vendorid': '051d', 
+'ups.timer.shutdown': '-1', 
+'ups.test.result': 'No test initiated', 
+'ups.firmware': '868.L3 -P.D', 
+'battery.mfr.date': '2015/05/08', 
+'ups.serial': '3B1519X19994  ', 
+'ups.productid': '0002', 
+'battery.runtime': '2552', 
+'battery.date': '2001/09/25', 
+'battery.voltage.nominal': '24.0', 
+'battery.type': 'PbAc', 
+'ups.mfr.date': '2015/05/08', 
+'ups.status': 'OL', 
+'ups.model': 'Back-UPS RS1000G', 
+'ups.beeper.status': 'disabled', 
+'battery.charge': '100', 
+'input.sensitivity': 'medium', 
+'input.transfer.low': '88'
+'input.transfer.high': '147', 
+'input.voltage': '121.0', 
+'input.voltage.nominal': '120', 
+'input.transfer.reason': 'input voltage out of range', 
+```
+
+Use the values from the left hand column.  Support is included for most values with 'ups', 'battery', and 'input' prefixes.
+
+```yaml
+sensor:
+  - platform: nut
+    name: UPS Name
+    host: 192.168.11.5
+    port: 3493
+    alias: ups_name
+    username: user
+    password: pass
+    resources:
+      - ups.load
+      - ups.realpower.nominal
+      - input.voltage
+      - battery.runtime
+```