local_file camera component documenatation (#554)

* Documenation for local_file camera component

* Update camera.local_file.markdown

source/_components/camera.local_file.markdown

@@ -0,0 +1,33 @@
+---
+layout: page
+title: "Local File"
+description: "Instructions how to use Local File as a Camera within Home Assistant."
+date: 2016-06-12 17:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: file.png
+ha_category: Camera
+ha_iot_class: "Local Polling"
+ha_release: 0.22
+---
+
+The `Local File ` allows you to integrate any readable image file from disk into Home Assistant as a Camera.
+If the image is updated in the file system the image displayed in Home Assistant will also be updated.
+This can for example be used with various camera platforms that save a temporary images localy.
+
+```yaml
+# Example configuration.yaml entry
+camera:
+  platform: local_file
+  name: Local File
+  file_path: /tmp/image.jpg
+```
+
+Configuration variables:
+
+ - **name** (optional): Name of the camera
+ - **file_path** (required): File to serve as the camera.
+ 
+The given **file_path** must be an existing file because the camera platform setup make a readable check on it.