feat(distrobox): leave an additional_packages example (ublue-os#371)

etc/distrobox/distrobox.ini

@@ -1,5 +1,7 @@
 [ubuntu]
 image=ghcr.io/ublue-os/ubuntu-toolbox:latest
+#additional_packages=" " 
+#export=" "
 init=false
 nvidia=false
 pull=true
@@ -9,9 +11,13 @@ replace=true
 # Add more distros and then use: 
 # distrobox assemble create --replace --file /etc/distrobox/distrobox.ini
 # This will replace your distroboxes in place
+# Tip: Use additional_packages as declarative config!
+# See https://distrobox.privatedns.org/usage/distrobox-assemble/
 
 #[fedora]
 #image=registry.fedoraproject.org/fedora-toolbox:latest
+#additional_packages="ansible lynx chromium neofetch cmus"
+#export="app chromium"
 #init=false
 #nvidia=false
 #pull=true
@@ -24,4 +30,4 @@ replace=true
 #nvidia=false
 #pull=true
 #root=false
-#replace=true
+#replace=true