docs: function renderTemplateFiles (skipInterpolation) {
    skipInterpolation = typeof skipInterpolation === 'string'
      ? [skipInterpolation]
      : skipInterpolation
    return (files, metalsmith, done) => {
      const keys = Object.keys(files)
      const metalsmithMetadata = metalsmith.metadata()
      async.each(keys, (file, next) => {
        // skipping files with skipInterpolation option
        if (skipInterpolation && multimatch([file], skipInterpolation, { dot: true }).length) {
          return next()
        }
        const str = files[file].contents.toString()
        // do not attempt to render files that do not have mustaches
        if (!/{{([^{}]+)}}/g.test(str)) {
          return next()
        }
        render(str, metalsmithMetadata, (err, res) => {
          if (err) {
            err.message = `[${file}] ${err.message}`
            return next(err)
          }
          files[file].contents = Buffer.from(res)
          next()
        })
      }, done)
    }
  }