Hi @ram1, this content is generated by scraping other elements’ pages. To edit the result, you’ll need to edit one of these pages. To be more precise, the HTMLRefTablemacro fetches the summary of each page that has the “Web Components” tag or which is the HTML page for <shadow>.
Basically, on the article in reading mode, click the link of the element you’re interested in and edit the first sentences. After that, refresh the https://developer.mozilla.org/en-US/docs/Web/HTML/Element page (it might takes few seconds for changes to be applied).