Maybe talk about lazy loading in these guides?

[jenweber]

See https://github.com/ember-cli/ember-cli/issues/7908

[villander]

@jenweber this already documented on ember-engines guides. And lazy loading will not be a exclusively feature of ember-engines, but of embroider as well. So I thinks that we must avoid an overhead info for while.

[villander]

makes sense @jenweber?