added key show_monitors_tip

src/lang/en.rs

@@ -53,5 +53,6 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("empty_lan_tip", "Oh no, it looks like we haven't discovered any peers yet."),
         ("empty_address_book_tip", "Oh dear, it appears that there are currently no peers listed in your address book."),
         ("identical_file_tip", "This file is identical with the peer's one."),
+        ("show_monitors_tip", "Show monitors in toolbar")
         ].iter().cloned().collect();
 }