extract tarball, convert md to html and save on disk

gulpfile.js

gulp.task('extractTarball', async function() {
  let markdownStream = lazypipe()
  .pipe(markdown)
  .pipe(pug, {template: 'layout/layout.pug'});

  let tarStream = await tarball.getTarball();

  let tarPipe = tarStream
  .pipe(extract())
  .pipe(gulpif('*.md', markdownStream()))
  .pipe(gulp.dest('src/reference/test'));
  return tarPipe;
});