Fix acme.sh home environment

Using-systemd-units-instead-of-cron.md

@@ -8,6 +8,8 @@ After=network-online.target
 
 [Service]
 Type=oneshot
+# Directory where the acme.sh script resides.
+Environment="HOME=/"
 ExecStart=/path/to/acme.sh <your acme.sh arguments here>
 # acme.sh returns 2 when renewal is skipped (i.e. certs up to date)
 SuccessExitStatus=0 2