docs: def declare_type_info(config):
      """Lookup type info from app configuration."""
      settings = config.registry.settings
      settings['_type_info'] = []
      for line in settings['exports-allowable-types'].splitlines():
          if not line.strip():
              continue
          type_name, type_info = line.strip().split(':', 1)
          type_info = type_info.split(',', 3)
          settings['_type_info'].append((type_name, {
              'type_name': type_name,
              'file_extension': type_info[0],
              'mimetype': type_info[1],
              'user_friendly_name': type_info[2],
              'description': type_info[3],
              }))