update rationale section in readme

README.md

@@ -11,7 +11,7 @@ See [Op](src/main/kotlin/net/eksb/obsdc/Op.kt) for a list of operations.
 
 ## Configuration
 
-Configuration is in `$XDG_CONFIG_HOME/net.eksb.obsdc/config.properties`
+Configuration is read from `$XDG_CONFIG_HOME/net.eksb.obsdc/config.properties`
 
 ### Configuration options
 
@@ -19,6 +19,15 @@ Configuration is in `$XDG_CONFIG_HOME/net.eksb.obsdc/config.properties`
 * `port` - OBS websocket port (default: `4455`)
 * `password` - OBS websocket password (required)
 
+### systemd
+
+A systemd unit file ([obsdc.service](src/main/dist/obsdc.service)) is included.
+
+1. Copy the file to `~/.config/systemd/user/`.
+2. Edit the `ExecStart` line for where you have installed obsdc.
+3. `systemctl --user enable obsdc`
+4. `systemctl --user start obsdc`
+
 ## Build
 
 `gradle build`
@@ -49,9 +58,13 @@ using an `Obs`.
 I usually code on a 4k monitor in portrait mode. To show what I am doing on video calls,
 I use OBS to share that monitor, but it is a 2160x4096 source in a 1920x1080 scene.
 
-I have [a macropad](https://www.keebmonkey.com/products/megalodon-dual-layer-knob-macro-pad) with two knobs.
-My [window manager](https://swaywm.org/) is configured to call `obsdc-signal` with `PAN_UP`/`PAN_DOWN` for the
-keys emitted by one knob and `PAN_RIGHT`/`PAN_LEFT` for the keys emitted by the other knob.
+I have
+[a macropad](https://keeb.io/collections/bdn9-collection/products/bdn9-rev-2-3x3-9-key-macropad-rotary-encoder-and-rgb)
+with three knobs.
+My [window manager](https://swaywm.org/) is configured to call `obsdc-signal` with
+`PAN_UP`/`PAN_DOWN` for the keys emitted by the left knob,
+`PAN_RIGHT`/`PAN_LEFT` for the keys emitted by the right knob, and
+`SCENE_NEXT`/`SCENE_PREV` for the keys emitted by the center knob.
 The regular keys on the macropad are mapped to the other actions.
 
-So now I can quickly control what people can see without having to focus (or even make visible) the OBS window.
+So now I can quickly control what people can see without having to focus (or even make visible) the OBS window.

src/main/dist/obsdc.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=OBSDC
+
+[Service]
+Type=dbus
+BusName=net.eksb.obsdc
+ExecStart=/opt/obsdc/bin/obsdc
+
+[Install]
+WantedBy=default.target

src/main/resources/simplelogger.properties

@@ -1 +1,2 @@
 org.slf4j.simpleLogger.log.net.eksb=debug
+org.slf4j.simpleLogger.log.org.freedesktop.dbus=debug