correct line length

Author: Fourchaux

src/libstd/panicking.rs

@@ -221,7 +221,7 @@ impl<'a> PanicInfo<'a> {
     ///
     /// panic::set_hook(Box::new(|panic_info| {
     ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred in file '{}' at line {}", location.file(), location.line());
+    ///        println!("panic occurred in file '{}' at line {}", location.file(), location.line());
     ///     } else {
     ///         println!("panic occurred but can't get location information...");
     ///     }