feat: add comment

Author: FoseFx

tests/ui/or_then_unwrap.rs

@@ -28,6 +28,7 @@ fn main() {
     let instance = SomeStruct {};
     let _ = instance.or(Some(SomeStruct {})).unwrap(); // should not trigger lint
 
+    // or takes no argument
     let instance = SomeOtherStruct {};
     let _ = instance.or().unwrap(); // should not trigger lint and should not panic