docs: document byte format

crates/serde/src/quantity.rs

@@ -3,6 +3,10 @@
 //! This is defined as a "hex encoded unsigned integer", with a special case of 0 being `0x0`.
 //!
 //! A regex for this format is: `^0x([1-9a-f]+[0-9a-f]*|0)$`.
+//!
+//! This is only valid for human-readable [`serde`] implementations.
+//! For non-human-readable implementations, the format is unspecified.
+//! Currently, it is uses a fixed-width big-endian byte-array.
 
 use private::ConvertRuint;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
@@ -88,7 +92,7 @@ pub mod vec {
     }
 }
 
-/// Private implementation details of the [`quantity`] module.
+/// Private implementation details of the [`quantity`](self) module.
 mod private {
     #[doc(hidden)]
     pub trait ConvertRuint: Copy + Sized {