Document using Skip in an Android app

[aabewhite]

Other than our skipapp-travelposter and skipapp-travelposters-native samples (which need to be updated as they've fallen behind our adoption of the latest Kotlin/Compose compiler) and the blog post about them, we have virtually no instructions on how to properly integrate Skip into an Android app. This is important for people who want to only share part of their code. We need to cover not only "skip export" but everything else, including:

• How to add other necessary dependencies to the Android project, like Coil and CommonMark if they're sharing SwiftUI code.
• How to bootstrap Skip's reference to the Android Context through ProcessInfo.
• Be more clear about how to display SwiftUI views in an existing Android app.