Minor change to power meter docs.

power/images/IMAGES.md

@@ -5,6 +5,10 @@
 ![Interior](./interior.JPG)
 Interior construction - slightly out of date: doesn't show cable glands.
 
+## Screenshots.
+
+**These look much better in reality than in my pictures.**
+
 ![Microwave](./microwave.JPG)
 Microwave oven.
 ![Plot](./plot.JPG)