docs: add loginctl linger

README.md

@@ -3,6 +3,8 @@
 ```bash
 # ---------------------------
 # 1. Environment setup (Ubuntu 20.04)
+
+# - assumes the account name is "deployer"
 # ---------------------------
 
 # install deps
@@ -51,6 +53,9 @@ sudo nano /etc/systemd/user/tower.service
 sudo systemctl daemon-reload
 systemctl --user start tower.service
 systemctl --user enable tower.service
+
+# Enable systemd persistence
+loginctl enable-linger deployer
 ```
 
 ### Debug