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];