[gnome-user-docs] Translators note

[Petr Kovář <pmkovar src gnome org>]

commit ec1aedc09ed086c747a89a72486ae34bf3dd2b9a
Author: Gunnar Hjalmarsson <gunnarhj ubuntu com>
Date:   Sun Mar 18 17:26:35 2018 +0100

    Translators note
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794187

 gnome-help/C/files-preview.page |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/gnome-help/C/files-preview.page b/gnome-help/C/files-preview.page
index 2a6d06b..a659e92 100644
--- a/gnome-help/C/files-preview.page
+++ b/gnome-help/C/files-preview.page
@@ -32,8 +32,9 @@
 <note if:test="platform:ubuntu" style="important">
   <p>You need to have <app>Sushi</app> installed on your computer to perform
   these steps.</p>
-  <p><link style="button" href="apt:gnome-sushi">Install
-  <app>Sushi</app></link></p>
+  <p its:locNote="Translators: This button is only shown on Ubuntu, where this
+  link format is preferred over 'install:gnome-sushi'."><link style="button"
+  href="apt:gnome-sushi">Install <app>Sushi</app></link></p>
 </note>
 
 <p>You can quickly preview files without opening them in a full-blown