Update the description

Author: Seulgi Kim

Cargo.toml

@@ -1,10 +1,14 @@
 [package]
 name = "finally-block"
-version = "0.1.0"
+version = "0.1.1"
 authors = ["Seulgi Kim <[email protected]>"]
 edition = "2018"
 license = "MIT"
 repository = "http://github.com/CodeChain-io/rust-finally-block"
 keywords = ["control", "raii", "finally", "block"]
+description = """
+Final block is a block that is executed when it dropped.
+It helps a user to write the deferred statements that should be executed even some statements return early.
+"""
 
 [dependencies]

README.md

@@ -1,3 +1,17 @@
 # finally-block [![Build Status](https://travis-ci.com/CodeChain-io/rust-finally-block.svg?branch=master)](https://travis-ci.com/CodeChain-io/rust-finally-block) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 
-An emulation of finally block.
+Final block is a block that is executed when it dropped.
+It helps a user to write the deferred statements that should be executed even some statements return early.
+
+```rust
+function f(flag: &AtomicBool) -> Option<()> {
+    if some_condition {
+        let _f = finally(|| {
+            flag.store(true, Ordering::SeqCst);
+        });
+        some_function(flag)?;
+    } else {
+        another_function()?;
+    }
+}
+```