Print the public key in PKey example

//!

//! # Example

//!

//! Generate a 2048-bit RSA public/private key pair.

//! Generate a 2048-bit RSA public/private key pair and print the public key.

//!

//! ```rust

//!

//!

//! use openssl::rsa::Rsa;

//! use openssl::pkey::PKey;

//! use std::str;

//!

//! fn main() {

//!     let rsa = Rsa::generate(2048).unwrap();

//!     let pkey = PKey::from_rsa(rsa).unwrap();

//!

//!     let pub_key: Vec<u8> = pkey.public_key_to_pem().unwrap();

//!     println!("{:?}", str::from_utf8(pub_key.as_slice()).unwrap());

//! }

//! ```