The help output from the Fastly CLI is consumed by the Fastly Developer Hub to produce online documentation: https://www.fastly.com/documentation/reference/cli
Part of the documentation is to provide additional usage examples and links to APIs used by the CLI commands (example: https://www.fastly.com/documentation/reference/clibackend/create/#examples).
These examples and API references are defined in pkg/app/metadata.json.