Update 20.classical-collisions/10.main/.gitkeep,...

Update 20.classical-collisions/10.main/.gitkeep, 20.classical-collisions/10.main/textbook.en.md, 20.classical-collisions/10.main/textbook.es.md, 20.classical-collisions/10.main/textbook.fr.md, 20.classical-collisions/20.overview/.gitkeep, 20.classical-collisions/20.overview/cheatsheet.en.md, 20.classical-collisions/20.overview/cheatsheet.es.md, 20.classical-collisions/20.overview/cheatsheet.fr.md, 20.classical-collisions/30.beyond/.gitkeep, 20.classical-collisions/30.beyond/annex.en.md, 20.classical-collisions/30.beyond/annex.es.md, 20.classical-collisions/30.beyond/annex.fr.md, 20.classical-collisions/.gitkeep files
Deleted 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/10.main/textbook.en.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/10.main/textbook.es.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/10.main/textbook.fr.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/20.overview/cheatsheet.en.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/20.overview/cheatsheet.es.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/20.overview/cheatsheet.fr.md, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/10.main/.gitkeep, 10.brainstorming-innovative-courses/entropy/n1/20.classical-chocks/30.beyond/annex.en.md files