default-apps: Correct Nautilus' app ID

Fixes: fb289fa0 "data: Reorganize default apps"
Resolves: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/8230
Signed-off-by: Simon McVittie <smcv@debian.org>
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3662>

data/default-apps/dash.txt

@@ -1,6 +1,6 @@
 org.gnome.Epiphany.desktop
 org.gnome.Calendar.desktop
-gnome.Nautilus.desktop
+org.gnome.Nautilus.desktop
 org.gnome.Software.desktop
 org.gnome.TextEditor.desktop
 org.gnome.Calculator.desktop