Fix typo, formulas typo
Fix:
- English typo (no space before punctuations
:;?!) - et.al -> et al.
- Parentheses in formula 4.1
- D U -> DU in formula 1.1
- Colon in Sources title (there must not be colons at the end of titles)
Gitlab was migrated to a new server. Everything should be back to normal and no visible change should remain. If you see anything wrong, please report them to https://forum.duniter.org/t/interventions-et-indisponibilite-des-forums-et-de-gitlab/7131/271
Fix:
:;?!)