message: Rephrase containerSelector description in README
diff: @@ -190,7 +190,7 @@ const embla = EmblaCarousel(emblaNode, options)
  </summary>
  <hr>
  <div>
  - This option allows for a custom query selector for the container that holds the slides, within the provided embla node. All immediate children of this container will be treated as slides.
  + This option allows for the use of a custom query selector to match the container that holds the slides, within the provided embla node. All immediate children of this container will be treated as slides.
  </div>
  <br>
  <div>
  @@ -221,6 +221,7 @@ const embla = EmblaCarousel(emblaNode, options)
  </p>
  ```javascript
  +const emblaNode = document.querySelector('.embla')
  const options = { containerSelector: '.my-classname' }
  const embla = EmblaCarousel(emblaNode, options)
  ```
  