[seahorse] Add translator comment

[Stefan Walter <stefw src gnome org>]

commit 2fd38024c4d186b46c2ed13bb410d20b76a61965
Author: Alexandre Franke <alexandre franke gmail com>
Date:   Sat Jul 9 10:18:50 2016 +0200

    Add translator comment
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768604

 common/util.vala |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/common/util.vala b/common/util.vala
index 62ecb62..2b333d8 100644
--- a/common/util.vala
+++ b/common/util.vala
@@ -56,6 +56,10 @@ namespace Util {
                var created_date = GLib.Date();
                created_date.set_time_t (time);
                var buffer = new char[128];
+               /* TRANSLATORS: this date (Year-month-day) is used to display
+                * when something happened, e.g. when a key was created. Feel
+                * free to put it in the correct order for your language.
+                */
                created_date.strftime(buffer, _("%Y-%m-%d"));
                return (string)buffer;
        }