xdg_shell: Update doc-test
//! ```no_run
//! # extern crate wayland_server;
//! #
-//! use smithay::wayland::shell::xdg::{xdg_shell_init, XdgRequest};
+//! use smithay::delegate_xdg_shell;
+//! use smithay::wayland::shell::xdg::{XdgShellState, XdgShellHandler, XdgRequest};
//!
-//! # let mut display = wayland_server::Display::new();
-//! let (shell_state, _) = xdg_shell_init(
-//! &mut display,
-//! // your implementation
-//! |event: XdgRequest, dispatch_data| { /* handle the shell requests here */ },
+//! # struct State { xdg_shell_state: XdgShellState }
+//! # let mut display = wayland_server::Display::<State>::new().unwrap();
+//! let xdg_shell_state = XdgShellState::new::<State, _>(
+//! &display.handle(),
//! None // put a logger if you want
//! );
//!
+//! // insert the xdg_shell_state into your state
+//! // ...
+//!
+//! // implement the necessary traits
+//! impl XdgShellHandler for State {
+//! fn xdg_shell_state(&mut self) -> &mut XdgShellState {
+//! &mut self.xdg_shell_state
+//! }
+//!
+//! fn request(&mut self, dh: &wayland_server::DisplayHandle, request: XdgRequest) {
+//! /* handle the shell requests here */
+//! }
+//! }
+//! delegate_xdg_shell!(State);
+//!
//! // You're now ready to go!
//! ```
//!
