book: use an example for signals example

book/src/getting-started/1-qobjects-in-rust.md

@@ -48,7 +48,9 @@ These CXX-Qt modules consist of multiple parts:
 - The `impl` of the `RustObj` struct (optional):
     - Contains any Rust code.
     - Functions marked with `#[invokable]` will be callable from QML and C++.
-<!-- TODO: Add Signals enum, once #67 lands -->
+- The `Signal` enum
+    - A normal Rust enum.
+    - Defines signals that are added to the QObject class
 
 CXX-Qt will then expand this Rust module into two separate parts:
 - A C++ subclass of QObject with the same name as the module

book/src/qobject/cpp_object.md

@@ -24,14 +24,7 @@ If there is a [`Signals` enum](./signals_enum.md) then you can call `emit_queued
 Note that `emit_immediate` is unsafe as it can cause deadlocks if the `Q_EMIT` is `Qt::DirectConnection` connected to a Rust invokable on the same QObject that has caused the `Q_EMIT`, as this would then try to lock the `RustObj` which is already locked.
 
 ```rust,ignore,noplayground
-impl RustObj {
-    #[invokable]
-    fn invokable(&self, cpp: &mut CppObj) {
-        unsafe { cpp.emit_immediate(Signal::Ready); }
-
-        cpp.emit_queued(Signal::DataChanged { data: 1 });
-    }
-}
+{{#include ../../../examples/qml_features/src/signals.rs:book_rust_obj_impl}}
 ```
 
 ## Threading