Update RubberduckUI.resx

Add Italian to available languages

Author: PhilCattivocaratere

Rubberduck.Resources/RubberduckUI.resx

@@ -1895,4 +1895,7 @@ Do you want to proceed?</value>
   <data name="DeclarationType_Document" xml:space="preserve">
     <value>document</value>
   </data>
-</root>
+  <data name="Language_IT" xml:space="preserve">
+    <value>Italian</value>
+  </data>
+</root>