- Enhance documentation and examples
- Add support for `click.Path(path_type=...)` as a type or a callable with an
annotated return type. Unsupported `path_type` values will raise `TypeError`.
- A new parameter is supported for `check_param_annotations`,
`known_type_names`, a mapping of type values to strings.
`check_param_annotations` will use this mapping in a best-effort fashion to
display the names of types in `BadAnnotation` errors.