Add alternate usage instructions

.cargo/README.md

@@ -27,7 +27,20 @@ cargo add chksum
 
 ## Usage
 
-Use the `chksum` function to calcualate digest of file, directory and so on.
+Use the `chksum` function with the desired algorithm to calcualate digest of file, directory and so on.
+
+```rust
+use chksum::{chksum, SHA2_256};
+
+let file = File::open(path)?;
+let digest = chksum::<SHA2_256>(file)?;
+assert_eq!(
+    digest.to_hex_lowercase(),
+    "44752f37272e944fd2c913a35342eaccdd1aaf189bae50676b301ab213fc5061"
+);
+```
+
+Alternatively, use the `chksum` function directly from the chosen hash module.
 
 ```rust
 use chksum::sha2_256;

README.md

@@ -27,7 +27,20 @@ cargo add chksum
 
 ## Usage
 
-Use the `chksum` function to calcualate digest of file, directory and so on.
+Use the `chksum` function with the desired algorithm to calcualate digest of file, directory and so on.
+
+```rust
+use chksum::{chksum, SHA2_256};
+
+let file = File::open(path)?;
+let digest = chksum::<SHA2_256>(file)?;
+assert_eq!(
+    digest.to_hex_lowercase(),
+    "44752f37272e944fd2c913a35342eaccdd1aaf189bae50676b301ab213fc5061"
+);
+```
+
+Alternatively, use the `chksum` function directly from the chosen hash module.
 
 ```rust
 use chksum::sha2_256;

src/lib.rs

@@ -19,7 +19,27 @@
 //!
 //! # Usage
 //!
-//! Use the [`chksum`] function to calcualate digest of file, directory and so on.
+//! Use the [`chksum`] function with the desired algorithm to calcualate digest of file, directory and so on.
+//!
+//! ```rust
+//! # use std::path::Path;
+//! use std::fs::File;
+//!
+//! # use chksum::Result;
+//! use chksum::{chksum, SHA2_256};
+//!
+//! # fn wrapper(path: &Path) -> Result<()> {
+//! let file = File::open(path)?;
+//! let digest = chksum::<SHA2_256>(file)?;
+//! assert_eq!(
+//!     digest.to_hex_lowercase(),
+//!     "44752f37272e944fd2c913a35342eaccdd1aaf189bae50676b301ab213fc5061"
+//! );
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! Alternatively, use the `chksum` function directly from the chosen hash module.
 //!
 //! ```rust
 //! # use std::path::Path;