Fix nits

[LimpidCrypto]

This is supposed to be an ongoing task. A collection of nits. Maybe just look into this task before pushing to development branch. Simply remove key point as soon as fixed.

• https://github.com/sephynox/xrpl-rust/blob/develop/src/core/addresscodec/mod.rs#L104 should be "Returns a decoded seed."
• https://github.com/sephynox/xrpl-rust/blob/develop/src/core/addresscodec/mod.rs#L477 should be "Returns the decoded bytes of the account public key."