Add newest tracks, and help intents

index.ts

app.intent('New', (conv: Conv) => {
  const newestTracks = conv.data.json.tracks.slice(0, 3)
  conv.ask('The last three tracks added to Tabletop Audio are: ' +
    newestTracks.map(track => track.track_title) +
    '. What do you want to listen to?')
  conv.ask(new Suggestions(...newestTracks.map(track => track.track_title)))
})

app.intent('Help', (conv: Conv) => {
  conv.ask('Tabletop Audio is the premier advertising-free, free-to-use, and user-supported ' +
    'ambient game audio site on the Internet. Visit the website to view a complete list of ' +
    'tracks. You can also ask me "What are the latest tracks", ask for a specific song like ' +
    `${conv.data.json.tracks[0].track_title}, or ask to play music from a genre like ` +
    `${conv.data.json.tracks[0].track_genre}. What do you want to do?`)
  conv.ask(new BasicCard({
    title: 'Tabletop Audio',
    image: new Image({
      url: 'https://images.tabletopaudio.com/header3.png',
      alt: 'Tabletop Audio banner image'
    }),
    buttons: new Button({
      title: 'View website',
      url: 'https://tabletopaudio.com'
    })
  }))
})