- Marketplace description, README and messages lead with .archify files
in YAML; Archify's JSON files and rendered HTML are described as also
supported, in their own README section and a supported-files table
- Rename the rendered-HTML editor to Archify HTML Viewer (it shared the
extension's name) and its command to Open in Archify HTML Viewer
- Empty or broken .archify files ask for valid YAML instead of JSON