Fix French translations

Fix French translations

- "supprimer" is a better translation than "écarter" for "discard"
- "actuel" is a better translation than "courant" for "current"
- "modifications" is a better translation than "changements" for change
- "journal des modifications" is a better translation than "journal des changements" for changelog
- The button "Remplir le journal des changements" for pages_edit_set_changelog caused a wrapping in the header, it is replaced by "Décrivez vos modifications"