Update cheatsheet.fr.md

12.temporary_ins/08.grad-div-rot/20.div/20.overview/cheatsheet.fr.md

@@ -36,8 +36,8 @@ div\,\overrightarrow{X}\color{black}{\;=\dfrac{d\Phi_X}{d\tau}}\,= &\dfrac{1}{r^
 <br>
 
 **$`\begin{align}\boldsymbol{\mathbf{
-div\,\overrightarrow{X}\color{black}{\;=\dfrac{d\Phi_X}{d\tau}}\,= &\dfrac{1}{r^2}\;\dfrac{\partial\,(r^2\,X_r}{\partial\,r}\\
+div\,\overrightarrow{X}\color{black}{\;=\dfrac{d\Phi_X}{d\tau}}\,= &\dfrac{1}{r^2}\;\dfrac{\partial\,(r^2\,X_r}{\partial\,r}}}\\
 \\
-& \quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,(sin\,\theta\,X_{\theta})}{\partial\,\theta}\\
+& \boldsymbol{\mathbf{\quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,(sin\,\theta\,X_{\theta})}{\partial\,\theta}}}\\
 \\
-& \quad\quad\quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}}}\end{align}`$**
+& \boldsymbol{\mathbf{\quad\quad\quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}}}\end{align}`$**