Add systemd setup instructions

SETUP.md

@@ -41,7 +41,26 @@ These instructions describe how to install and run the bridge manually from a cl
     * Note that on first use, you must enter a verification code on a smartphone version of KakaoTalk in order for the login to complete
 
 ## systemd
-Coming soon!
+The [systemd](systemd) directory provides sample service unit configuration files for running the bridge & node-kakao modules:
+
+* `matrix-appservice-kakao.service` for the bridge module
+* `matrix-appservice-kakao-node.service` for the node-kakao module
+
+To use them as-is, follow these steps after [initial setup](#initial-setup):
+
+1. Place/link your clone of this repository in `/opt/matrix-appservice-kakaotalk`
+    * If moving your repo directory after having already created a Python virtual environment for the bridge module, re-create the virtual environment after moving to ensure its paths are up-to-date
+    * Alternatively, clone it to `/opt/matrix-appservice-kakaotalk` in the first place
+1. Install the services as either system or user units
+    * To install as system units:
+        1. Copy/link the service files to a directory in the system unit search path, such as `/etc/systemd/system/`
+        1. Create the services' configuration directory with `sudo mkdir /etc/matrix-appservice-kakaotalk`
+        1. RECOMMENDED: Create the `matrix-appservice-kakaotalk` user on your system with `adduser` or an equivalent command, then uncomment the `User` and `Group` lines in the service files
+    * To install as user units:
+        1. Copy/link the service files to a directory in the user unit search path, such as `~/.config/systemd/user`
+        1. Create the services' configuration directory with `mkdir $XDG_CONFIG_HOME/matrix-appservice-kakaotalk`
+1. Copy the bridge & node-kakao module configuration files to the services' configuration directory as `config.yaml` and `node-config.json`, respectively
+1. Start the services now and on every boot boot with `[sudo] systemd [--user] enable --now matrix-appservice-kakaotalk{,-node}`
 
 ## Upgrading
 Simply `git pull` or `git rebase` the latest changes and rerun any installation commands (`npm install`, `pip install -Ur ...`).

systemd/matrix-appservice-kakaotalk-node.service

@@ -10,7 +10,7 @@ NotifyAccess=all
 WorkingDirectory=/opt/matrix-appservice-kakaotalk/node
 ConfigurationDirectory=matrix-appservice-kakaotalk
 RuntimeDirectory=matrix-appservice-kakaotalk
-ExecStart=/usr/bin/env node src/main.js --config ${CONFIGURATION_DIRECTORY}/config.json
+ExecStart=/usr/bin/env node src/main.js --config ${CONFIGURATION_DIRECTORY}/node-config.json
 Restart=on-failure
 RestartSec=3