Fix spelling RViz tutorial (#4232)

* Fix spelling RViz tutorial

Signed-off-by: Alejandro Hernández Cordero <[email protected]>

Author: ahcorde

source/Tutorials/Intermediate/RViz/RViz-User-Guide/RViz-User-Guide.rst

@@ -12,8 +12,8 @@ RViz User Guide
    :local:
 
 
-Backround
----------
+Background
+----------
 RViz is a 3D visualizer for the Robot Operating System (ROS) framework.
 
 Install or build rviz