Updated docs.

Author: peteches

docs/systemd_details.md

@@ -4,5 +4,10 @@ The first time tmux starts when '@continuum-boot' is set to 'on' tmux-continuum
 
 The command used to start the tmux server is determined via the '@systemd_tmux_server_start_cmd' option that can be set in .tmux.conf. (Remember to reload your configuration with `tmux source ~/.tmux.conf` afterwards.
 
-The default command to use is `new-session`. If you want more control over what sessions get started then you should set up your sessions in tmux.conf and set @systemd_tmux_server_start_cmd to 'start-server'
+The default command to use is `new-session -d`. If you want more control over what sessions get started then you should set up your sessions in tmux.conf and set @systemd_tmux_server_start_cmd to 'start-server'
+
+To control the tmux service you can use all the standard `systemctl` commands using the `--user` argument. eg to see if the tmux server has started:
+
+  systemctl --user status tmux.service
+