Fix simple spelling error

Signed-off-by: Steve Macenski <[email protected]>

tuning/index.rst

@@ -43,7 +43,7 @@ This was added due to quirks in some existing controllers whereas tuning the con
 
 Note: If using a non-holonomic, kinematically feasible planner (e.g. Smac Hybrid-A\*, Smac State Lattice), this is not a necessary behavioral optimization. This class of planner will create plans that take into account the robot's starting heading, not requiring any rotation behaviors. 
 
-This behavior is most optimially for: 
+This behavior is most optimally for: 
 
 - Robots that can rotate in place, such as differential and omnidirectional robots.
 - Preference to rotate in place when starting to track a new path that is at a significantly different heading than the robot’s current heading – or when tuning your controller for its task makes tight rotations difficult.