Fixed dunst startup sequence from async to sync

i3/.config/i3/config

@@ -226,15 +226,20 @@ bindsym XF86WebCam exec ~/.config/i3/scripts/webcam-toggle.sh
 # Numlock
 exec_always --no-startup-id numlockx on
 
+# Note:
+# `exec` commands are executed in order, but asynchronously;
+# In other words the commands are launched in sequence without waiting the previous command to finish.
+# In case a syncronous behaviour is desired, chain the commands with `&&` or group them in a script to be
+# launched an `exec` command.
+
 # Background
 exec --no-startup-id feh --bg-fill $HOME/Scaricati/northern_lights_by_aenami_dbbx471.png
 
 # Compositor
 exec --no-startup-id compton --config $HOME/.config/compton/config
 
-# Notification Manager
-exec --no-startup-id envsubst < ~/.config/dunst/dunstrc.template > ~/.config/dunst/dunstrc
-exec --no-startup-id dunst --config $HOME/.config/dunst/dunstrc
+# Notification Manager (dunst)
+exec --no-startup-id envsubst < ~/.config/dunst/dunstrc.template > ~/.config/dunst/dunstrc && dunst --config $HOME/.config/dunst/dunstrc
 
 # Pulseaudio
 ## Necessary if you have no DE (gnome, xfce, etc...) under i3.