WIP. Include code using doxygen special commands

Author: DavidSpielman

docs/page_customization.dox

@@ -101,38 +101,7 @@ The right column lists the Qt objects, the object names, and the classes the obj
 @par
 [linear_approach_modifier_widget.h](https://github.com/ros-industrial/noether/blob/dev/noether_gui/include/noether_gui/widgets/tool_path_modifiers/linear_approach_modifier_widget.h)
 
-```
-#pragma once
-
-#include <noether_gui/widgets.h>
-#include <noether_tpp/core/tool_path_modifier.h>
-
-namespace Ui
-{
-class Vector3dEditor;
-class LinearApproachModifier;
-}  // namespace Ui
-
-namespace noether
-{
-class LinearApproachToolPathModifierWidget : public ToolPathModifierWidget
-{
-public:
-  LinearApproachToolPathModifierWidget(QWidget* parent = nullptr);
-
-  ToolPathModifier::ConstPtr create() const override;
-
-  void configure(const YAML::Node&) override;
-  void save(YAML::Node&) const override;
-
-protected:
-  Ui::LinearApproachModifier* ui_;
-  Ui::Vector3dEditor* vector_editor_ui_;
-};
-
-}  // namespace noether
-
-```
+@include{lineno} noether_gui/include/noether_gui/widgets/tool_path_modifiers/linear_approach_modifier_widget.h
 
 @par
 The header file for the widget declares the QT creator UI elements (under the Ui namespace) and the Noether `ToolPathModifierWidget` class methods.