message: docs(content): updated 'Getting Started' CTA link
diff: <h2 class="hero-headline no-toc">RxJS</h2>
  <span class="hero-subheadline">Reactive Extensions Library for JavaScript</span>
  </div>
  - <a class="button hero-cta" href="/api">Get Started</a>
  + <a class="button hero-cta" href="/guide/overview">Get Started</a>
  </div>
  </section>
  