add comment on generate_composite_uuid describing what the method does

crates/bevy_reflect/src/lib.rs

@@ -50,6 +50,9 @@ pub use erased_serde;
 pub mod __macro_exports {
     use crate::Uuid;
 
+    // Generates a new UUID from the given UUIDs `a` and `b`,
+    // where the bytes are generated by a bitwise `a ^ b.rotate_right(1)`.
+    // The generated UUID will be a UUIDv4 (meaning that the bytes should be random, not e.g. derived from the system time).
     #[allow(clippy::unusual_byte_groupings)] // unusual byte grouping is meant to signal the relevant bits
     pub const fn generate_composite_uuid(a: Uuid, b: Uuid) -> Uuid {
         let mut new = [0; 16];