Add new examples to the explainer

[mrego]

As discussed on the AOM meeting today, we'd like to include more complex examples on the explainer, maybe mixing both delegation/import and reflection/export together talking about why components are writing in that way.

@nolanlawson and @Westbrook seem to have some examples that they can provide.

Probably one of these complex examples should be in the top of the explainer as a clear main use case and motivation for these proposals.