[gnome-boxes] empty-boxes: replaced "New" with "+"

[Felipe Borges <felipeborges src gnome org>]

commit b4a3420197ee1c76eb2f084314ea19f40d530d1e
Author: Adwait Rawat <adwait rawat gmail com>
Date:   Mon Sep 9 19:34:33 2019 +0900

    empty-boxes: replaced "New" with "+"
    
    Changed the  to a  because of the use of add-list-symbolic
    instead of the previously used button.
    
    Fixes #411

 data/ui/empty-boxes.ui | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/data/ui/empty-boxes.ui b/data/ui/empty-boxes.ui
index 54a3c16b..6e724c4f 100644
--- a/data/ui/empty-boxes.ui
+++ b/data/ui/empty-boxes.ui
@@ -92,7 +92,7 @@
                 <property name="use-markup">True</property>
                 <property name="halign">center</property>
                 <property name="vexpand">True</property>
-                <property name="label" translatable="yes">Just hit the &lt;b&gt;New&lt;/b&gt; button to 
create your first one.</property>
+                <property name="label" translatable="yes">Just hit the &lt;b&gt;+&lt;/b&gt; button to create 
your first one.</property>
                 <style>
                   <class name="dim-label"/>
                 </style>