Missing example explanation in example/README.md

[cmower]

@joaomoura24, could you add a small explanation to the example readme file please. It should go in here:

https://github.com/cmower/optas/tree/master/example#examples

For each example you added, please just describe very briefly what the point of the script is and also remember to mention the script.

[cmower]

Closing and adding to #63.