Add API for `markAsSaved` about node-feedly HOT 1 OPEN

// Add custom read later method
f.markSaved = (ids, cb) => {
  if (typeof ids === 'string') {
    ids = [ids]
  }
  return f._request(cb, '/v3/markers', 'POST', {
    entryIds: ids,
    type: 'entries',
    action: 'markAsSaved'
  })
};