[gnome-boxes] Add translator comment to explain 'Express Install'

[Christophe Fergeau <teuf src gnome org>]

commit 758680238d2f051e0e5e3d685fff834deba75b47
Author: Christophe Fergeau <cfergeau redhat com>
Date:   Mon Jul 2 12:40:30 2012 +0200

    Add translator comment to explain 'Express Install'
    
    https://bugzilla.gnome.org/show_bug.cgi?id=679229

 src/unattended-installer.vala |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/unattended-installer.vala b/src/unattended-installer.vala
index b534fa0..f5d392d 100644
--- a/src/unattended-installer.vala
+++ b/src/unattended-installer.vala
@@ -200,6 +200,8 @@ private abstract class Boxes.UnattendedInstaller: InstallerMedia {
         setup_table.row_spacing = 10;
 
         // First row
+        // Translators: 'Express Install' means that the new box installation will be fully automated, the user
+        // won't be asked anything while it's performed.
         var label = new Gtk.Label (_("Express Install"));
         label.halign = Gtk.Align.END;
         label.valign = Gtk.Align.CENTER;