doc: make line visible

src/libstd/io/stdio.rs

@@ -252,7 +252,7 @@ impl Stdin {
     ///
     /// - Pipe some text to it, e.g. `printf foo | path/to/executable`
     /// - Give it text interactively by running the executable directly,
-    //    in which case it will wait for the Enter key to be pressed before
+    ///   in which case it will wait for the Enter key to be pressed before
     ///   continuing
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {