message: docs(aio): fix links to quickstart on homepage
diff: <div class="hero background-superhero-paper is-large"><img
  src="assets/images/logos/angular/angular.svg" class="hero-logo"/>
  <h1 class="text-headline">One framework.<br>Mobile &amp; desktop.</h1><a
  - href="/docs/ts/latest/quickstart.html" md-button="md-button"
  + href="guide/quickstart" md-button="md-button"
  class="hero-cta mat-raised button button-large button-plain">Get Started</a>
  <announcement-bar class="announcement-bar">
  <div class="announcement-bar-slide cleafix is-visible"><img
  <div><img src="assets/images/home/loved-by-millions.png"></div>
  </div>
  </div>
  - <div class="cta-bar"><a href="/docs/ts/latest/quickstart.html" md-button="md-button"
  + <div class="cta-bar"><a href="guide/quickstart" md-button="md-button"
  class="button button-large button-shield mat-raised mat-primary">Get
  Started</a></div>
  </div>
  