Update README.md

update navigation commands and gif animations

Author: fjp

README.md

@@ -126,15 +126,25 @@ roslaunch diffbot_control diffbot.launch world_name:='$(find diffbot_gazebo)/wor
 
 #### Navigation
 
-To navigate the robot in the simulation run this command:
+To navigate the robot in the Gazebo simulator in `db_world.world` run the command:
 
 ```console
-roslaunch diffbot_navigation diffbot.launch world_name:='$(find diffbot_gazebo)/worlds/turtlebot3_world.world'
+roslaunch diffbot_navigation diffbot.launch
 ```
 
-Navigate the robot in a known map from the running [`map_server`](http://wiki.ros.org/map_server) using the [2D Nav Goal in RViz](http://wiki.ros.org/navigation/Tutorials/Using%20rviz%20with%20the%20Navigation%20Stack#A2D_Nav_Goal).
+This uses a previously mapped map of `db_world.world` (found in [`diffbot_navigation/maps`](./diffbot_navigation/maps/)) that is served by
+the [`map_server`](http://wiki.ros.org/map_server). With this you can use the [2D Nav Goal in RViz](http://wiki.ros.org/navigation/Tutorials/Using%20rviz%20with%20the%20Navigation%20Stack#A2D_Nav_Goal) directly to let the robot drive autonomously in the `db_world.world`.
 
-[![DiffBot navigation](https://raw.githubusercontent.com/ros-mobile-robots/ros-mobile-robots.github.io/main/docs/resources/navigation/diffbot-navigation-gazebo-turtlebot3-world-small.gif)](https://youtu.be/2SwFTrJ1Ofg)
+[![DiffBot navigation](https://media.githubusercontent.com/media/ros-mobile-robots/ros-mobile-robots.github.io/main/docs/resources/navigation/db_world-nav.gif)](https://youtu.be/2SwFTrJ1Ofg)
+
+To run the `turtlebot3_world.world` (or your own stored world and map) use the same `diffbot_navigation/launch/diffbot.launch` file but change
+the `world_name` and `map_file` arguments to your desired world and map yaml files:
+
+```console
+roslaunch diffbot_navigation diffbot.launch world_name:='$(find diffbot_gazebo)/worlds/turtlebot3_world.world' map_file:='$(find diffbot_navigation)/maps/map.yaml'
+```
+
+[![DiffBot navigation](https://github.com/ros-mobile-robots/ros-mobile-robots.github.io/raw/main/docs/resources/navigation/diffbot-navigation-gazebo-turtlebot3-world-small.gif)](https://youtu.be/2SwFTrJ1Ofg)
 
 #### SLAM
 
@@ -154,6 +164,12 @@ Then explore the world with the [`teleop_twist_keyboard`](http://wiki.ros.org/te
 
 [![DiffBot slam](https://raw.githubusercontent.com/ros-mobile-robots/ros-mobile-robots.github.io/main/docs/resources/slam/diffbot-slam.gif)](https://youtu.be/gLlo5V-BZu0)
 
+When you finished exploring the new world, use the [`map_saver`](http://wiki.ros.org/map_server#map_saver) node from the [`map_server`](http://wiki.ros.org/map_server) package to store the mapped enviornment:
+
+```
+rosrun map_server map_saver -f ~/map
+```
+
 
 ### DiffBot Control in Gazebo