Update README.md

README.md

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 # Airplay Music Watcher
 
-A golang service which watches for devices starting or stopping playing airplay audio
+A golang service which watches for devices starting or stopping playing airplay audio. When a device starts or stops, you can issue system command line tasks.
+
+This is primarily useful for home automations. For example: detecting music playing on an airplay dongle, and turning on your receiver (via a smart switch, or IR command). I use it with homebridge and an IR blaster to turn a nice vintage receiver on an off for airplay.
+
+## Note on event timing
+
+If you start or stop playing it sends the commands immediately. If you simply pause, the stop command comes eventually but not instantly. From experimentation, pausing triggers a stop event after approximately 8 minutes.
+
+## Setup
+
+1) Download the appriopiate binary for your system from the latest release: https://github.com/scosman/airplay-music-watcher/releases 
+2) Create a config file using JSON format below. You can add as many entries as you want. The device_name and action are used to identify the trigger, and the command and command_args are what is run when the event is triggered
+3) Run the server via command line and ensure it works as you want it to: `./airplay-music-watcher ./your_json_config.json`
+4) Setup the command to run on boot using systemd, launchd, or your daemon manager of choice!
+
+## JSON Config File Example
+
+This json file would say "stereo starting" when the Airplay device named "Stereo" starts playing, and say "stereo stopping" when it stops.
+
+```
+{
+    "actions": [
+        {
+            "device_name": "Stereo",
+            "action": "start_playing",
+            "command": "say",
+            "command_args": "'stereo starting'"
+        },
+        {
+            "device_name": "Stereo",
+            "action": "end_playing",
+            "command": "say",
+            "command_args": "'stereo stopping'"
+        }
+    ]
+}
+```