- Update network policy section to reflect thinking about cross-space
  resource sharing

- Add fields for provisioning/updating service instances
- Add user-provided service instances
- Break service bindings into their own section. They don't fit well
  nested under service instances: Apps depend on services; services
  don't depend on apps. For "app" bindings, it might make sense to nest
  under apps, but "key" and "route" bindings don't make sense under
  apps. Instead, break bindings into a top-level node.

- Fix inconsistent health check configuration
- Add `scale` node to processes to organize related nodes

- To add more hierarchy and closer match API design

- Small style updates and typo fixes
- Add additional risk to declarative manifests