Update nx584 alarm platform docs

Adds a logo and clarifies some things.

source/_components/alarm_control_panel.nx584.markdown

@@ -7,10 +7,12 @@ sidebar: true
 comments: false
 sharing: true
 footer: true
+logo: networx.png
 ha_category: Alarm
 ---
 
-The `nx584` platform is consuming the information provided by a NetworX-based alarm panels and should work for any such panel equipped with a NX584 serial interface module like Caddx, GE, or Interlogix. This includes NX-4/6/8/8E, where the NX8E has this interface built-in.
+The `nx584` platform provides integration with GE, Caddx, Interlogix (and other brands) alarm panels that support the NX584 interface module (or have it built in). Supported panels include NX4/6/8/8E. Actual integration is done through [pynx584](http://github.com/kk7ds/pynx584) which is required for this to work.
+
 
 To enable this, add the following lines to your `configuration.yaml`:
 
@@ -18,10 +20,10 @@ To enable this, add the following lines to your `configuration.yaml`:
 # Example configuration.yaml entry
 alarm_control_panel:
   platform: nx584
-  host: IP_ADDRESS
+  host: ADDRESS
 ```
 
 Configuration variables:
 
-- **host** (*Optional*): The IP address of the pynx584 backend server. Defaults to `localhost:5007`.
+- **host** (*Optional*): This is the host connection string (host:port) for the nx584 server process. If unset, it is assumed to be `localhost:5007`, which will work if the server process is running on the same system as home-assistant.