mention that `"s".code` is a compile-time feature (see #4270)

typer.ml

@@ -3868,7 +3868,7 @@ and handle_display ctx e_ast iscall with_type p =
 		let fields = match fst e_ast with
 			| EConst(String s) when String.length s = 1 ->
 				let cf = mk_field "code" ctx.t.tint e.epos in
-				cf.cf_doc <- Some "The character code of this String literal";
+				cf.cf_doc <- Some "The character code of this character (resolved at compile-time)";
 				cf.cf_kind <- Var { v_read = AccNormal; v_write = AccNever };
 				PMap.add cf.cf_name cf fields
 			| _ ->