Fix typos and doc comments
//!
//! "The spend authorizing key ask, proof authorizing key (ak, nsk),
//! full viewing key (ak, nk, ovk), incoming viewing key ivk, and each
-//! diversied payment address addr_d = (d, pk_d ) are derived from sk,
+//! diversified payment address addr_d = (d, pk_d ) are derived from sk,
//! as described in [Sapling Key Components][ps]."
//!
//! [ps]: https://zips.z.cash/protocol/protocol.pdf#saplingkeycomponents
