message: landing page: update banner to point to v4.0 release tag
diff: @@ -191,7 +191,7 @@ const codeBlocks: CodeBlockProps[] = [
  const header = 'Lightweight Charts Documentation';
  const paragraph = `Lightweight Charts is a library for creating interactive financial charts. This documentation site provides all the information needed to get started with Lightweight Charts and help you make the most of its features.`;
  -const showBanner = false;
  +const showBanner = true;
  function Index(): JSX.Element {
  return (
  @@ -199,7 +199,7 @@ function Index(): JSX.Element {
  {showBanner ? (
  <Banner
  text="Big news! Version 4.0 of Lightweight Charts is now available"
  - link="https://www.tradingview.com/blog/en/lightweight-charts-v3-7-is-now-faster-than-ever-27576/"
  + link="https://github.com/tradingview/lightweight-charts/releases/tag/v4.0.0"
  linkText="Read more"
  />
  ) : (
  