std::io: Use re-exported pathes in examples.

We use re-exported pathes (e.g. std::io::Command) and original ones
(e.g. std::io::process::Command) together in examples now. Using
re-exported ones consistently avoids confusion.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>

src/libstd/io/process.rs

@@ -476,8 +476,8 @@ impl Process {
     ///
     /// ```no_run
     /// # #![allow(experimental)]
-    /// use std::io::process::{Command, ProcessExit};
-    /// use std::io::IoResult;
+    /// use std::io::{Command, IoResult};
+    /// use std::io::process::ProcessExit;
     ///
     /// fn run_gracefully(prog: &str) -> IoResult<ProcessExit> {
     ///     let mut p = try!(Command::new("long-running-process").spawn());