Handle ActionHasher::hash result in example (#81)

* Handle ActionHasher::hash result in example

* Use a clearer expect message.

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: leynos

src/hasher.rs

@@ -19,7 +19,7 @@
 //!     pool: None,
 //!     restat: false,
 //! };
-//! let hash = ActionHasher::hash(&action);
+//! let hash = ActionHasher::hash(&action).expect("failed to hash action");
 //! assert!(!hash.is_empty());
 //! ```