docs: Update crate-level documentation (#6)

Author: sorairolake

CHANGELOG.adoc

@@ -14,6 +14,12 @@ All notable changes to this project will be documented in this file.
 The format is based on https://keepachangelog.com/[Keep a Changelog], and this
 project adheres to https://semver.org/[Semantic Versioning].
 
+== {compare-url}/v0.1.0\...HEAD[Unreleased]
+
+=== Changed
+
+* Update crate-level documentation ({pull-request-url}/6[#6])
+
 == {project-url}/releases/tag/v0.1.0[0.1.0] - 2026-03-03
 
 === Added

src/lib.rs

@@ -5,6 +5,9 @@
 //! The `kcipher2` crate is an implementation of the [KCipher-2] stream cipher
 //! as described in [RFC 7008].
 //!
+//! Cipher functionality is accessed using traits from re-exported [`cipher`]
+//! crate.
+//!
 //! # Examples
 //!
 //! ```