Added documentation to Amcrest camera sensors (#1763)

* Added documentation to Amcrest camera sensors

* Added scan_interval option and changed release to 0.37

source/_components/sensor.amcrest.markdown

@@ -0,0 +1,43 @@
+---
+layout: page
+title: "Amcrest IP Camera"
+description: "Instructions how to integrate Amcrest IP cameras sensors within Home Assistant."
+date: 2017-01-13 10:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: amcrest.png
+ha_category: Sensor
+ha_release: 0.37
+---
+
+The `amcrest` sensor allows you to integrate your [Amcrest](https://amcrest.com/) IP camera in Home Assistant.
+
+To enable the `amcrest` sensors on your camera, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+sensor:
+  - platform: amcrest
+    host: IP_ADDRESS
+    username: USERNAME
+    password: PASSWORD
+    monitored_conditions:
+      - motion_detector
+      - sdcard
+      - ptz_preset
+```
+
+Configuration variables:
+
+- **host** (*Required*): The IP address or hostname of your camera. If using hostname, make sure the DNS works as expected.
+- **username** (*Required*): The username for accessing your camera.
+- **password** (*Required*): The password for accessing your camera.
+- **name** (*Optional*): This parameter allows you to override the name of your camera. The default is "Amcrest Camera".
+- **port** (*Optional*): The port that the camera is running on. The default is 80.
+- **scan_interval** (*Optional*): Defines the update interval of the sensor in seconds. The default is 10 seconds.
+- **monitored_conditions** array (*Required*): Conditions to display in the frontend. The following conditions can be monitored.
+  - **motion_detector**: Return True/False when a motion is detected
+  - **sdcard**: Return the SD card usage by reporting the total and used space
+  - **ptz_preset**: Return the number of PTZ preset positions configured for the given camera