Rename figure 3.07

Author: hollasch

books/RayTracingTheRestOfYourLife.html

@@ -1339,7 +1339,8 @@
 is $\frac{1}{A}$. What is it on the area of the unit sphere that defines directions? Fortunately,
 there is a simple correspondence, as outlined in the diagram:
 
-  ![Figure [light-pdf]: Projection of light shape onto PDF](../images/fig.light-pdf.jpg)
+  ![Figure [shape-onto-pdf]: Projection of light shape onto PDF
+  ](../images/fig-3.07-shape-onto-pdf.jpg)
 
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