message: Add description to the init event
diff: @@ -1704,7 +1704,7 @@ embla.destroy()
  const embla = EmblaCarousel(emblaNode, options)
  const onInitCallback = () => {
  - console.log('The carousel has just been initialized.')
  + console.log('The carousel is ready to rock.')
  }
  embla.on('init', onInitCallback)
  @@ -1793,11 +1793,17 @@ embla.on('scroll', () => {
  <details>
  <summary>
  - Under construction...
  + Fire your callback when the carousel mounts.
  </summary>
  <hr>
  <div>
  - Under construction...
  + This event fires the given callback when the carousel has initialised and its
  + <a href="#api">
  + <code>API</code>
  + </a> is ready to use. Note that the init event only fires once upon the first initialisation and won't trigger when invoking
  + <a href="#changeOptions">
  + <code>changeOptions</code>
  + </a> or similar.
  </div>
  <br>
  <div>
  @@ -1806,7 +1812,7 @@ embla.on('scroll', () => {
  </a>
  &nbsp;
  <a href="#">
  - <code>CodeSandbox</code>
  + <code>CodeSandbox (upcoming)</code>
  </a>
  </div>
  <br>
  @@ -1816,6 +1822,12 @@ embla.on('scroll', () => {
  ```javascript
  const embla = EmblaCarousel(emblaNode, options)
  +
  +const onInitCallback = () => {
  + console.log('The carousel is ready to rock.')
  +})
  +
  +embla.on('init', onInitCallback)
  ```
  <hr>
  