docs: bytes wrapper example (#2714)

Author: davidsemakula

integration-tests/public/bytes/lib.rs

@@ -1,5 +1,22 @@
 #![cfg_attr(not(feature = "std"), no_std, no_main)]
 
+/// Example for using bytes wrapper types (i.e. `ink::sol::FixedBytes<N>` and
+/// `ink::sol::DynBytes`) as message and event arguments.
+///
+/// # Note
+///
+/// In Solidity ABI encoding, `uint8[]` and `uint8[N]` are encoded differently from
+/// `bytes` and `bytesN`. In Rust/ink!, `Vec<u8>` and `[u8; N]` are mapped to Solidity's
+/// `uint8[]` and `uint8[N]` representations, so there's a need for dedicated Rust/ink!
+/// types (i.e. `ink::sol::DynBytes` and `ink::sol::FixedBytes<N>`) that map to Solidity's
+/// `bytes` and `bytesN` representations.
+///
+/// # References
+///
+/// - <https://use-ink.github.io/ink/ink_primitives/sol/struct.FixedBytes.html>
+/// - <https://use-ink.github.io/ink/ink_primitives/sol/struct.DynBytes.html>
+/// - <https://use.ink/docs/v6/background/solidity-metamask-compatibility#rustink-to-solidity-abi-type-mapping>
+
 #[ink::event]
 pub struct FixedBytesPayload {
     pub data: ink::sol::FixedBytes<8>,
@@ -21,7 +38,7 @@ pub mod bytes {
     pub struct Bytes;
 
     impl Bytes {
-        /// Creates a new bytes smart contract.
+        /// Creates a new smart contract.
         #[ink(constructor)]
         #[allow(clippy::new_without_default)]
         pub fn new() -> Self {