docs(wallet): reword the `next_unused_address` doc
Adds an example on what `used` stands for, and make it explicit that it
has the same behavior as `Wallet::reveal_next_address` in the scenario
where all previously revealed addresses have been used.
docs(wallet): fix typo in doc comment
}
/// Get the next unused address for the given `keychain`, i.e. the address with the lowest
- /// derivation index that hasn't been used.
+ /// derivation index that hasn't been used in a transaction.
///
- /// This will attempt to derive and reveal a new address if no newly revealed addresses
- /// are available. See also [`reveal_next_address`](Self::reveal_next_address).
+ /// This will attempt to reveal a new address if all previously revealed addresses have
+ /// been used, in which case the returned address will be the same as calling [`Wallet::reveal_next_address`].
///
/// **WARNING**: To avoid address reuse you must persist the changes resulting from one or more
/// calls to this method before closing the wallet. See [`Wallet::reveal_next_address`].