More layout examples

[Alex2772]

Although I consider the layout management is fully documented https://aui-framework.github.io/develop/group__layout__managers.html people are generally struggling with it, especially with Expanding behaviour.

I suggest adding more layout examples, based on real life cases. I also suggest coloring each container to its own color in these samples, as well as pointing to devtools and its CTRL+hover feature which is helpful in layout understanding.