adding descriptions to pictures css code example

Example: how to use figure and caption in html

<!-- Just an image -->
<figure>
  <img
  src="https://developer.mozilla.org/static/img/favicon144.png"
  alt="The beautiful MDN logo.">
</figure>

<!-- Image with a caption -->
<figure>
  <img
  src="https://developer.mozilla.org/static/img/favicon144.png"
  alt="The beautiful MDN logo.">
  <figcaption>MDN Logo</figcaption>
</figure>