Add Camera Proxy documentation (#4863)

* Add Camera Proxy documentation

* Minor typos

* Update camera.proxy.markdown

source/_components/camera.proxy.markdown

@@ -0,0 +1,61 @@
+---
+layout: page
+title: "Camera Proxy"
+description: "Instructions how to integrate a camera proxy within Home Assistant."
+date: 2018-03-08 19:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category: Camera
+ha_release: 0.65
+---
+
+
+The `proxy` camera platform allows you to pass another camera's output through post-processing routines and generate a new camera with the post-processed output.
+
+The current post-processing supports resizing the image/MJPEG as well as limiting the maximum refresh rate.
+
+The current proxy capabilities are intended to reduce the camera bandwidth for slower internet connections.
+
+To enable this camera in your installation, you must first have an existing working camera configured in Home Assistant.  Next, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+camera:
+  - platform: proxy
+    entity_id: camera.<existingcamera>
+    max_stream_width: 360
+    max_image_width: 720
+```
+
+Configuration variables:
+
+- **entity_id** (*Required*): The ID of another Home Assistant camera to post-process.
+- **name** (*Optional*): This parameter allows you to override the name of your camera.
+- **max_image_width** (*Optional*): The maximum width of single images taken from the camera (aspect ratio will be maintained).
+- **max_stream_width** (*Optional*): The maximum width of the MJPEG stream from the camera (aspect ratio will be maintained).
+- **image_quality** (*Optional*): The quality level used for resulting JPEG for snapshots (default: 75).
+- **stream_quality** (*Optional*): The quality level used for resulting MJPEG streams (default: 75).
+- **image_refresh_rate** (*Optional*): The minimum time in seconds between generating successive image snapshots.
+- **force_resize** (*Optional*): Resize the image even if the resulting image would take up more bandwidth than the original.
+- **cache_images** (*Optional*): Preserve the last image and re-send in the case the camera is not responding.
+
+
+## {% linkable_title Examples %}
+
+Example of using a Camera proxy along with a Foscam camera:
+
+```yaml
+camera:
+  - platform: foscam
+    ip: 192.168.1.10
+    username: foscam_camera
+    password: camera_password
+    name: mycamera
+  - platform: proxy
+    entity_id: camera.mycamera
+    max_stream_width: 360
+    max_image_width: 480
+    image_refresh_rate: 5.0
+```