[gtranslator] Added missing mnemonic to language assistant

[Daniel Mustieles García <dmustieles src gnome org>]

commit dfac9495e41865df1464ebabffcc5f43c4b4720d
Author: Daniel Mustieles <daniel mustieles contractor bbva com>
Date:   Fri Mar 29 12:21:30 2019 +0100

    Added missing mnemonic to language assistant

 src/gtr-lang-button.ui | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/gtr-lang-button.ui b/src/gtr-lang-button.ui
index fe5c693b..bf0d9e42 100644
--- a/src/gtr-lang-button.ui
+++ b/src/gtr-lang-button.ui
@@ -67,7 +67,8 @@
       <object class="GtkLabel">
         <property name="visible">True</property>
         <property name="can_focus">False</property>
-        <property name="label" translatable="yes">Choose Language</property>
+        <property name="label" translatable="yes">Choose _Language</property>
+        <property name="use_underline">True</property>
       </object>
     </child>
   </template>