add ignore file for research example

research/derive_order/use_macros/src/lib.rs

@@ -1,3 +1,5 @@
+// keepsorted: ignore file
+
 #[cfg(test)]
 mod tests {
     use derive_macros::{First, Second};
@@ -12,7 +14,6 @@ mod tests {
 
     #[test]
     fn test_first_second() {
-        // keepsorted: ignore block
         #[derive(First, Second)] // <- This is expected to work.
         struct MyStruct;
 
@@ -21,7 +22,6 @@ mod tests {
 
     #[test]
     fn test_second_first() {
-        // keepsorted: ignore block
         #[derive(Second, First)] // <- Seems the order is not important.
         struct MyStruct;