Update textbook.en.md

12.temporary_ins/05.coordinates-systems/30.cylindrical-coordinates/10.main/textbook.en.md

@@ -105,7 +105,7 @@ in $`z_M`$ on the $`Oz`$ axis will be $`(z_M, 0, 0)`$.
 
 * *CS320*
 
-! *Note :* The first two cylindrical coordinates of a point $`M`$ are the polar coordinates
+*Note :* The first two cylindrical coordinates of a point $`M`$ are the polar coordinates
 of the point $`m_{xy}`$ in the plane $`xOy`$ (plan $`z=0`$). They are also the polar 
 coordinates of the poin $`M`$ in the plane $`z=z_M`$.