fix doc root

//! println!("{}", Error::get().unwrap());

//! ```

#![warn(missing_docs)]

#![doc(html_root_url = "https://docs.rs/openssl-errors/0.1")]

#![doc(html_root_url = "https://docs.rs/openssl-errors/0.2")]

use cfg_if::cfg_if;

use libc::{c_char, c_int};