in quickstart package, articles have an intro image.
The code `<div class="article-header-wrap">
<div class="article-full-image" style="background-image:url(/images/2018/12/01/12_large.jpg)"></div>
<div class="article-header">
<h1 itemprop="headline">
webcams </h1>
</div>
</div>
`
how to change image there ?