Update 12.temporary_ins/95.electromagnetism-in-media/10.propagation-lhi-media/10.main/textbook.fr.md

Update 12.temporary_ins/90.electromagnetism-in-vacuum/10.maxwell-equations/20.overview/cheatsheet.fr.md

Update 12.temporary_ins/95.electromagnetism-in-media/10.propagation-lhi-media/10.main/textbook.fr.md