update file.

README.md

@@ -8,7 +8,7 @@ This repo provides instructions on the installation and use of code on the Stret
 3. [Teleoperating Stretch](teleoperating_stretch.md)
 4. [Internal State of Stretch](internal_state_of_stretch.md)
 5. [RViz Basics](rviz_basics.md)
-6. [Navigation Stack]
+6. [Navigation Stack
](navigation_stack.md)
 7. [MoveIt! Basics]
 8. [Perception]
 9. [Microphone Array]

example_3.md

@@ -1,13 +1,13 @@
 ## Example 3
 
-![image](images/balloon.gif)
-
+![image](images/balloon.png)
 
 
 ```
 python marker.py
 ```
 
+![image](images/balloon.gif)
 
 ```python
 #!/usr/bin/env python