Assistant: Create a JavaScript to shrink screenshots automatically and open them on click

Screenshots of full screen in the installation instructions are useful to clarify the context. But they can be very big and disrupt the readibility of text instructions. A solution proposed in #9206-note_19 would be to have a JavaScript to display thumbnails by default and full size images on click.

Parent Task: #8580 (closed)

Original created by @sajolida on 10246 (Redmine)