An example about contour plot

[jake484]

hi, I write an example about contour plot and animation when l learned how to use Stipple. I met some problems and I solved them. I think this example may help people understand Stipple better. So, I hope this example can be added to StippleDemos. If allowed, I will start a pull request.

This is the example:

[AbhimanyuAryan]

@jake484 sure go ahead. Add this in StippleDemos > Advanced Examples > Contour Plots Dir with it's dedicated Project.toml + [compat]. [compat] is required because we aggressively pushing for Stipple v1 and we don't want the example to break with newer versions with API changes.

Thanks for your contribution to Stipple. I'll merge it right away 😃