Extend the study case with how to deserialize with borsh

Fix issue #21

README.md

@@ -132,6 +132,11 @@ fn main() -> Result<(), Error> {
     // Dump the serialized database into a file as an encrypted container.
     let container = cocoon.dump(encoded, &mut file)?;
 
+    // Let's look at how to decrypt the container and parse it back.
+    let mut file = File::open("target/test.db").unwrap();
+    let encoded = cocoon.parse(&mut file).unwrap();
+    let decoded = Database::try_from_slice(&encoded).unwrap();
+
     Ok(())
 }
 ```

src/lib.rs

@@ -123,14 +123,14 @@
 //! In the end, you use [`Cocoon`] to put the final image into an encrypted container.
 //!
 //! ```
-//! use borsh::BorshSerialize;
+//! use borsh::{BorshDeserialize, BorshSerialize};
 //! use cocoon::{Cocoon, Error};
 //!
 //! use std::collections::HashMap;
 //! use std::fs::File;
 //!
 //! // Your data can be represented in any way.
-//! #[derive(BorshSerialize)]
+//! #[derive(BorshDeserialize, BorshSerialize)]
 //! struct Database {
 //!     inner: HashMap<String, String>,
 //! }
@@ -154,6 +154,11 @@
 //!     // Dump the serialized database into a file as an encrypted container.
 //!     let container = cocoon.dump(encoded, &mut file)?;
 //!
+//!     // Let's look at how to decrypt the container and parse it back.
+//!     let mut file = File::open("target/test.db").unwrap();
+//!     let encoded = cocoon.parse(&mut file).unwrap();
+//!     let decoded = Database::try_from_slice(&encoded).unwrap();
+//!
 //!     Ok(())
 //! }
 //! ```