Update 12.temporary_ins/05.coordinates-systems/30.cylindrical-coordinates/20.overview/cheatsheet.fr.md

Update 12.temporary_ins/05.coordinates-systems/30.cylindrical-coordinates/20.overview/cheatsheet.fr.md

Deleted 12.temporary_ins/90.electromagnetism-in-vacuum/05.Electromagnetism-introduction/20.electromagnetism-learning-pattern/30.electromagnetism-chronology/.gitkeep