message: Apply suggestions from code review
  More typos fixed.
diff: @@ -117,12 +117,12 @@ impl Digest {
  /// Hashes a raw Merkle root and leaf count to firm the final Merkle hash.
  ///
  /// To avoid pre-image attacks, the final hash that is based upon the number of leaves in the
  - /// merkle tree and the root hash is prepended with a padding to ensure it is longer than the
  + /// Merkle tree and the root hash is prepended with a padding to ensure it is longer than the
  /// actual chunk size.
  ///
  /// Without this feature, an attacker could construct an item that is only a few bytes long but
  /// hashes to the same value as a much longer, chunked item by hashing `(len || root hash of
  - /// longer items Merkle tree root)`.
  + /// longer item's Merkle tree root)`.
  ///
  /// This function computes the correct final hash by ensuring the hasher used has been
  /// initialized with padding before. For efficiency reasons it uses a memoized hasher state
  