Fix ReflectKind description wording (#15498)

# Objective

The "zero-sized" description was outdated and misleading.

## Solution

Changed the description to just say that it's an enumeration (an enum)

crates/bevy_reflect/src/kind.rs

@@ -1,9 +1,10 @@
+use thiserror::Error;
+
 #[cfg(feature = "functions")]
 use crate::func::Function;
 use crate::{Array, Enum, List, Map, PartialReflect, Set, Struct, Tuple, TupleStruct};
-use thiserror::Error;
 
-/// A zero-sized enumeration of the "kinds" of a reflected type.
+/// An enumeration of the "kinds" of a reflected type.
 ///
 /// Each kind corresponds to a specific reflection trait,
 /// such as [`Struct`] or [`List`],
@@ -272,9 +273,10 @@ impl ReflectOwned {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use std::collections::HashSet;
 
+    use super::*;
+
     #[test]
     fn should_cast_ref() {
         let value = vec![1, 2, 3];