Update cheatsheet.en.md

12.temporary_ins/90.electromagnetism-in-vacuum/10.maxwell-equations/20.overview/cheatsheet.en.md

@@ -679,7 +679,7 @@ I recognize here the law of conservation of charge.
   $`\color{blue}{\scriptsize{\text{which you can rewrite:}}}`$      
   <br>
   **$`\mathbf{
-  \text{div}\,\left(\dfrac{\overrightarrow{E}\times\overrightarrow{B}}{\mu_0}\right)}`$   
+  \text{div}\,\left(\dfrac{\overrightarrow{E}\times\overrightarrow{B}}{\mu_0}\right)}`$
   $`\mathbf{\quad = -\,\vec{j}\cdot\overrightarrow{E}
   \,-\,\dfrac{\partial}{\partial t}\,\left(
   \dfrac{\epsilon_0\,E^2}{2}\,+\,\dfrac{B^2}{2\,\mu_0}