More layout examples

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.

Start with the linked layout management documentation and review how Expanding behavior is currently explained. Add real-life layout examples with distinct container colors, and point readers to devtools and its CTRL+hover feature; the documentation is done when these examples make layout behavior easier to understand.

Written by the indexing model from the issue text.