Add example of passing struct to task function

[morisja]

Thanks for the very useful library!
I needed to pass more than a single integer to the task, this PR demonstrates passing a struct. I also updated gitignore to avoid committing the build artifact.

[Pithikos]

thanks @morisja for this. However I think it's best to keep examples separated as to make it friendly for beginners and less overwhelming.

I suggest if you could move your example as a separate one into ./examples unless you have another suggestion