Improve Cross building with Conan using two profiles

[uilianries]

Conan 1.24 is now more than 1 year old and CCI advanced a lot in terms of cross-building support (M1) and dual profile support. However, we only have a small section for official documentation:

https://docs.conan.io/en/latest/systems_cross_building/cross_building.html#conan-v1-24-and-newer

It would be great adding new examples, which follow CCI usage, because of maturity and stability proves so far.

Related to https://cpplang.slack.com/archives/C41CWV9HA/p1628262139428700 /cc @SpaceIm