static _generateForPackageJSON(config) {
    let packageJSON = '';
    let packagePath = '';
    try {
      packageJSON = fs.readFileSync(config.package, {encoding: 'utf-8'});
      packagePath = path.resolve(config.package);
    } catch (e) {
      // ignore
    }

    const tag = {
      kind: 'packageJSON',
      content: packageJSON,
      longname: packagePath,
      name: path.basename(packagePath),
      static: true,
      access: 'public'
    };

    return tag;
  }
generate package doc
@param {ESDocConfig} config
@returns {Tag}
@private