[gnome-control-center] Add context to "Add Printer" to disambiguate the string

[Piotr Drąg <piotrdrag src gnome org>]

commit 9e14dd2c6f9a38a161c7c189fc49baf1fda85fd8
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Wed Jan 18 15:40:58 2017 +0100

    Add context to "Add Printer" to disambiguate the string
    
    Many languages may need to translate a button differently than
    a window title.

 panels/printers/printers.ui |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/panels/printers/printers.ui b/panels/printers/printers.ui
index 9623394..a67ff64 100644
--- a/panels/printers/printers.ui
+++ b/panels/printers/printers.ui
@@ -17,7 +17,7 @@
         <property name="visible">True</property>
         <property name="sensitive">True</property>
         <property name="use_underline">True</property>
-        <property name="label" translatable="yes">Add Printer</property>
+        <property name="label" translatable="yes" context="button">Add Printer</property>
         <style>
           <class name="suggested-action"/>
         </style>