First major update of src/2_coordinates.md

src/2_coordinates.md

@@ -70,8 +70,7 @@ the angular coordinate $\varphi$ is dimensionless.
 
 <figure markdown>
   ![image](figures/Coordinates_7_0.svg)
-  <figcaption>In this example of a polar plot, you can distinguish the radial coordinate (0.2, 0.4 etc.)
-from the angular one expressed in degrees ($0^\circ$, $45^\circ$ etc.).</figcaption>
+  <figcaption>In this example of a polar plot, you can distinguish the radial coordinate (0.2, 0.4 etc.) \\from the angular one expressed in degrees ($0^\circ$, $45^\circ$ etc.).</figcaption>
 </figure>
 
 
@@ -134,7 +133,7 @@ We can use the same arguments also for the area: since the different
 segments are approximately perpendicular, we find the area by simply
 multiplying them:
 
-!!! info "Surface element in polar coordinates
+!!! info "Surface element in polar coordinates"
     	$$dA = r dr d\varphi.$$
 
 This is an important formula to remember for integrating in polar