Codespell fixes.

1-ProceduralProgramming/4-Functions.ipynb

5-UsefulConceptsAndSTL/1-ErrorHandling.ipynb

5-UsefulConceptsAndSTL/6-SmartPointers.ipynb

6-InRealEnvironment/1-SetUpEnvironment.ipynb

6-InRealEnvironment/4b-Demo/5-FixByPragmas-common/pragma.hpp

6-InRealEnvironment/4b-Demo/README.md

6-InRealEnvironment/6-Tools.ipynb

Changelog.md

HandsOn/1-ProceduralProgramming/Solution/exercise10.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise11.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise12.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise4.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise5.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise6.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise7.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise8.cpp

HandsOn/1-ProceduralProgramming/Solution/exercise9.cpp

HandsOn/2-ObjectProgramming/Solution/exercise13.cpp

HandsOn/2-ObjectProgramming/Solution/exercise14.cpp

HandsOn/2-ObjectProgramming/Solution/exercise15.cpp