Add html tag figure

• use the right HTML tags for images (described {ref}here <image-tag-example>)

(image-tag-example)=

Example of image tag

This was found in the MUDE Archive, Issue 29.

It looks like the figure tag

<figure>
  <IMG SRC='...'>
</figure>

is not supported. but the img tag is:

<img src="...">

see examples here (no figure tag mentioned for HTML, only Markdown)