Update Getting-Started-with-Balance-Ball.md (#1168)

Fix typos

docs/Getting-Started-with-Balance-Ball.md

 
 **Note**: You can train using an executable rather than the Editor. To do so,
 follow the intructions in [Using an
-Execuatble](Learning-Environment-Executable.md).
+Executable](Learning-Environment-Executable.md).
 
 ### Observing Training Progress