process: Add an example with reading input line-by-line
//! }
//! ```
//!
+//! We can also read input line by line.
+//!
+//! ```no_run
+//! extern crate futures;
+//! extern crate tokio_core;
+//! extern crate tokio_process;
+//! extern crate tokio_io;
+//!
+//! use std::io;
+//! use std::process::{Command, Stdio, Output};
+//!
+//! use futures::{BoxFuture, Future, Stream};
+//! use tokio_core::reactor::Core;
+//! use tokio_process::{CommandExt, Child};
+//!
+//! fn get_lines(mut cat: Child) -> BoxFuture<((), Output), io::Error> {
+//! let stdout = cat.stdout().take().unwrap();
+//! let reader = io::BufReader::new(stdout);
+//! let lines = tokio_io::io::lines(reader);
+//! let cycle = lines.for_each(|l| {
+//! println!("Line: {}", l);
+//! Ok(())
+//! });
+//! cycle.join(cat.wait_with_output()).boxed()
+//! }
+//!
+//! fn main() {
+//! let mut cmd = Command::new("cat");
+//! let mut cat = cmd.stdout(Stdio::piped());
+//! let mut core = Core::new().unwrap();
+//! let child = cat.spawn_async(&core.handle()).unwrap();
+//! core.run(get_lines(child)).unwrap();
+//! }
+//!
+//! ```
+//!
//! # Caveats
//!
//! While similar to the standard library, this crate's `Child` type differs
