Add more info on example plot

README.md

@@ -189,7 +189,7 @@ BlackBoxOptimizer.**plot_convergence**(_ax_=`None`, _yscale_=`None`)
 
 Plot the running best gain/loss over the course of all previous trials. If passed, `ax` should be the [matplotlib axis](https://matplotlib.org/api/axes_api.html) to plot on and `yscale` should be the scale for the y axis.
 
-For example:
+For example (generated by running BBopt's [`keras` example](https://github.com/evhub/bbopt/blob/master/bbopt-source/examples/keras_example.py)):
 
 ![plot_convergence example](https://i.imgur.com/4dbGisY.png)