updated readme

Author: jpmvferreira

README.md

@@ -97,7 +97,10 @@ $ cd mnt
 > ```
 > systemctl --user start stag@<name>:<full path>
 > ```
-> Systemd may warn about the use of "/", but these warnings can be ignored.
+> Systemd will warn you about using `/`, to avoid issues, replace all `/` with `-`, e.g.:
+> ```
+> systemctl --user enable now stag@wallpapers:-home-user-wallpapers-
+> ```
 
 Add files to your repository as you would in any directory, by copying or moving them into the mount point. For demonstration purposes, let's create the following files