Add sample training images with credits

README.md

@@ -12,4 +12,13 @@ Filippo Varini, Dan Morris and the Community Fish Detector contributors
  	<li><a href="https://github.com/filippovarini/community-fish-detector">Learn more</a></li>
  	<li><a href="https://github.com/filippovarini/community-fish-detector#citing-this-work">Cite</a></li>
  	<li><a href="https://github.com/filippovarini/community-fish-detector">License</a></li>
-</ul>
+</ul>
+
+## Sample images
+
+Four frames from the training data, in `examples/`. Credits:
+
+- `examples/1.jpg`: Roboflow Fish dataset (CC0), Community Fish Detection Dataset via LILA BC
+- `examples/2.jpg`: Deep Vision dataset (CC BY 4.0), Community Fish Detection Dataset via LILA BC
+- `examples/3.jpg`: Roboflow Fish dataset (CC0), Community Fish Detection Dataset via LILA BC
+- `examples/4.jpg`: MIT Sea Grant River Herring (CDLA-Permissive), Community Fish Detection Dataset via LILA BC