Add doxygen doc in nav2_bt_navigator header files (#1282)

* Add doxygen doc in nav2_bt_navigator header files

* Address PR feedback

nav2_bt_navigator/include/nav2_bt_navigator/bt_navigator.hpp

@@ -30,20 +30,61 @@
 
 namespace nav2_bt_navigator
 {
-
+/**
+ * @class nav2_bt_navigator::BtNavigator
+ * @brief An action server that uses behavior tree for navigating a robot to its
+ * goal position.
+ */
 class BtNavigator : public nav2_util::LifecycleNode
 {
 public:
+  /**
+   * @brief A constructor for nav2_bt_navigator::BtNavigator class
+   */
   BtNavigator();
+  /**
+   * @brief A destructor for nav2_bt_navigator::BtNavigator class
+   */
   ~BtNavigator();
 
 protected:
-  // The lifecycle node interface
+  /**
+   * @brief Configures member variables
+   *
+   * Initializes action server for "NavigationToPose"; subscription to
+   * "goal_sub"; and builds behavior tree from xml file.
+   * @param state Reference to LifeCycle node state
+   * @return SUCCESS or FAILURE
+   */
   nav2_util::CallbackReturn on_configure(const rclcpp_lifecycle::State & state) override;
+  /**
+   * @brief Activates action server
+   * @param state Reference to LifeCycle node state
+   * @return SUCCESS or FAILURE
+   */
   nav2_util::CallbackReturn on_activate(const rclcpp_lifecycle::State & state) override;
+  /**
+   * @brief Deactivates action server
+   * @param state Reference to LifeCycle node state
+   * @return SUCCESS or FAILURE
+   */
   nav2_util::CallbackReturn on_deactivate(const rclcpp_lifecycle::State & state) override;
+  /**
+   * @brief Resets member variables
+   * @param state Reference to LifeCycle node state
+   * @return SUCCESS or FAILURE
+   */
   nav2_util::CallbackReturn on_cleanup(const rclcpp_lifecycle::State & state) override;
+  /**
+   * @brief Called when in shutdown state
+   * @param state Reference to LifeCycle node state
+   * @return SUCCESS or FAILURE
+   */
   nav2_util::CallbackReturn on_shutdown(const rclcpp_lifecycle::State & state) override;
+  /**
+   * @brief Called when in error state
+   * @param state Reference to LifeCycle node state
+   */
   nav2_util::CallbackReturn on_error(const rclcpp_lifecycle::State & state) override;
 
   using ActionServer = nav2_util::SimpleActionServer<nav2_msgs::action::NavigateToPose>;
@@ -51,13 +92,20 @@ protected:
   // Our action server implements the NavigateToPose action
   std::unique_ptr<ActionServer> action_server_;
 
-  // The action server callback
+  /**
+   * @brief Action server callbacks
+   */
   void navigateToPose();
 
-  // Goal pose initialization on the blackboard
+  /**
+   * @brief Goal pose initialization on the blackboard
+   */
   void initializeGoalPose();
 
-  // A subscription and callback to handle the topic-based goal published from rviz
+  /**
+   * @brief A subscription and callback to handle the topic-based goal published
+   * from rviz
+   */
   void onGoalPoseReceived(const geometry_msgs::msg::PoseStamped::SharedPtr pose);
   rclcpp::Subscription<geometry_msgs::msg::PoseStamped>::SharedPtr goal_sub_;