why

We should:

1. have a live example in the repo for documentation purposes
2. have an example on which to discuss V2 API changes Addon API: proposal #1212
3. improve our test coverage for "core" addons (how??)

what

Modify examples/test-cra to use all core addons with realistic use cases:

• actions
• centered
• events
• graphql
• info
• knobs
• links
• notes
• options