systemd: Add timers and services to keep git repos up-to-date

Yes, systemd. In my user repo. It's awesome.

.config/systemd/user/dot-fetch.timer

@@ -0,0 +1,11 @@
+# vim:ft=systemd:
+[Unit]
+Description=Dot fetch timer
+
+[Timer]
+Persistent=true
+OnBootSec=15min
+OnCalendar=*-*-* 22:00:00
+
+[Install]
+WantedBy=default.target