Finish Specifications

[robbiemc]

This repo has explainers, often quite detailed, that cover most IWA functionality, and a spec for IsolatedContext, which covers most of the security properties required to enable powerful capabilities. IWA functionality should be covered by a proper spec(s) as well.

• [ ] Integrity block v2
• [ ] isolated-app: scheme and loading behavior
• [ ] Installation
• [ ] Update manifest
• [ ] IWA navigation restrictions
• [ ] permissions_policy manifest field
• [ ] version manifest field