Update documentation for Extension Registry Support

As we're working on Project Firefly Extension Registry and its support via CLI and SDKs, we will need to update the existing documentation to take this in account, especially:

- App bootstrapping flow
- App update flow
- App deploy flow
- App publishing & approval flow

Start by locating the existing documentation for app bootstrapping, updating, deploying, and publishing and approval. Read how the Project Firefly Extension Registry is supported through the CLI and SDKs, then update each listed flow so the documentation accounts for that support. Done means all four flows reflect the Extension Registry behavior.

Written by the indexing model from the issue text.