code: function readDirSync (dir, allFiles = []) {
    const files = fs.readdirSync(dir).map(f => join(dir, f))
    allFiles.push(...files)
    files.forEach(f => {
      fs.statSync(f).isDirectory() && readDirSync(f, allFiles)
    })
    return allFiles
  }
docs: Reads content directory and return all files
  @param  {String} dir      Content path
  @param  {Array}  allFiles Partial list of files and directories
  @return {Array}           List of files and directories