Indent 4 spaces instead of 2

Author: carols10cents

src/libstd/macros.rs

@@ -138,8 +138,8 @@ macro_rules! println {
 /// fn write_to_file_using_match() -> Result<(), io::Error> {
 ///     let mut file = try!(File::create("my_best_friends.txt"));
 ///     match file.write_all(b"This is a list of my best friends.") {
-///       Ok(_) => (),
-///       Err(e) => return Err(e),
+///         Ok(_) => (),
+///         Err(e) => return Err(e),
 ///     }
 ///     println!("I wrote to the file");
 ///     Ok(())