message: updated demo_turtlebot3_navigaiton.launch with rgbd_sync
diff: </include>
  <group ns="rtabmap">
  + <node pkg="rtabmap_ros" type="rgbd_sync" name="rgbd_sync" output="screen">
  + <remap from="rgb/image" to="/camera/rgb/image_raw"/>
  + <remap from="depth/image" to="/camera/depth/image_raw"/>
  + <remap from="rgb/camera_info" to="/camera/rgb/camera_info"/>
  + </node>
  +
  <node name="rtabmap" pkg="rtabmap_ros" type="rtabmap" output="screen" args="$(arg rtabmap_args)">
  <param name="database_path" type="string" value="$(arg database_path)"/>
  <param name="frame_id" type="string" value="base_footprint"/>
  - <param if="$(eval model=='waffle')" name="subscribe_rgb" type="bool" value="true"/>
  - <param unless="$(eval model=='waffle')" name="subscribe_rgb" type="bool" value="false"/>
  - <param if="$(eval model=='waffle')" name="subscribe_depth" type="bool" value="true"/>
  - <param unless="$(eval model=='waffle')" name="subscribe_depth" type="bool" value="false"/>
  + <param name="subscribe_rgb" type="bool" value="false"/>
  + <param name="subscribe_depth" type="bool" value="false"/>
  + <param if="$(eval model=='waffle')" name="subscribe_rgbd" type="bool" value="true"/>
  + <param unless="$(eval model=='waffle')" name="subscribe_rgbd" type="bool" value="false"/>
  <param name="subscribe_scan" type="bool" value="true"/>
  <param name="approx_sync" type="bool" value="true"/>
  <!-- inputs -->
  <remap from="scan" to="/scan"/>
  <remap from="odom" to="/odom"/>
  - <remap from="rgb/image" to="/camera/rgb/image_raw"/>
  - <remap from="depth/image" to="/camera/depth/image_raw"/>
  - <remap from="rgb/camera_info" to="/camera/rgb/camera_info"/>
  + <remap from="rgbd_image" to="rgbd_image"/>
  <!-- output -->
  <remap from="grid_map" to="/map"/>
  