Show appropriate feature flags in docs

src/libgraphviz/lib.rs

@@ -47,7 +47,8 @@
 //! which is cyclic.
 //!
 //! ```rust
-//! # #![feature(rustc_private, core, into_cow)]
+//! #![feature(rustc_private, core, into_cow)]
+//!
 //! use std::borrow::IntoCow;
 //! use std::io::Write;
 //! use graphviz as dot;
@@ -149,7 +150,8 @@
 //! entity `&sube`).
 //!
 //! ```rust
-//! # #![feature(rustc_private, core, into_cow)]
+//! #![feature(rustc_private, core, into_cow)]
+//!
 //! use std::borrow::IntoCow;
 //! use std::io::Write;
 //! use graphviz as dot;
@@ -207,7 +209,8 @@
 //! Hasse-diagram for the subsets of the set `{x, y}`.
 //!
 //! ```rust
-//! # #![feature(rustc_private, core, into_cow)]
+//! #![feature(rustc_private, core, into_cow)]
+//!
 //! use std::borrow::IntoCow;
 //! use std::io::Write;
 //! use graphviz as dot;