Provide `--format` or `--output` options

There might be different use cases for this tool, so it should support multiple output options for max flexibility:

* json (useful for API or `jq` parsing for other CLI uses)
* markdown (useful for GH comments)
* English (for pasting to a jira ticket or into slack)
* table (for visual rendering)

Bonus:

* BYOT (bring your own template)