Update cheatsheet.fr.md

12.temporary_ins/10.electrostatics-vacuum/40.gauss-theorem-applications/25.cylindrical-charge-distributions/10.gauss-integral/20.overview/cheatsheet.fr.md

@@ -49,7 +49,7 @@ $`\def\Ssclosed{\mathscr{S}_{\scriptsize\bigcirc}}`$
 $`\def\PSopen{\mathscr{S}_{\smile}}`$
 $`\def\PSclosed{\mathscr{S}_{\displaystyle\tiny\bigcirc}}`$
 <!--essai-->
-$`\def\CalS{\mathcal{S}}`$
+$`\def\calS{\mathcal{S}}`$
 
 
 *Cours en construction*, **non validé**.