wrong name when calling the image of the nanoprims, not png but jpg

Author: sara-mokhtari

sasmodels/models/nanoprisms.py

@@ -10,7 +10,7 @@
 
 We consider particles having the shape of a right prism of length L and a cross section made of a regular polygon with n sides as illustrated in the figure below.
 
-.. figure:: img/nanoprisms_geometry.png
+.. figure:: img/nanoprisms_geometry.jpg
 
 The size of a regular polygon can be characterized by its edge length E or by R, the circumradius of the polygon shown in black in the figure, with :