Update 00.brainstorming-pedagogical-teams/45.synthesis-structuring/30.classical-mechanics/05.first-steps/textbook.es.md

entrainement suite Demo2 master patch 67370

See merge request !48

# Conflicts:
#   12.temporary_ins/05.coordinates-systems/20.cartesian-coordinates/30.beyond/annex.fr.md

Update 12.temporary_ins/20.magnetostatics-vacuum/20.causes-stationary-magnetic-field/20.overview/cheatsheet.fr.md