Expose dependency checking

[villander]

Explain the manual verification of dependencies that is needed right now.

[Charizard]

@villander Seems like we already have this in the guides here. It's present under Managing multiple addon versions.

[villander]

@Charizard this is about management dependencies - ember-engines/ember-engines#502

[villander]

For this one, we need to cover all scenarios and provide clear usage with ember-cli-addon-guard -https://github.com/dgeb/ember-cli-addon-guard

[gabrielcsapo]

I think we can add onto the information created in #92 to highlight how dependency issues like these could be fixed by using ember-cli-addon-guard. The explicit information on how to use it should live in https://github.com/dgeb/ember-cli-addon-guard.