Missing @since tag

cf. dd9c9a69 "Add the 'quoteright' key to the
list of available keyboard shortcuts."

Change-Id: Ia064782505e317ee3d1c3622c273eb892e477b5e

offapi/com/sun/star/awt/Key.idl

@@ -363,6 +363,7 @@ published constants Key
     const short SEMICOLON = 1317;
 
 
+    /** @since LibreOffice 4.3 **/
     const short QUOTERIGHT = 1318;