I want to modify an article.hbs template to include text at the top of the article body

Hi Sharon,
 
A good place to add text in article_page.hbs for these purposes could be right above the article's title:
 

<article id="main-content" class="article">
  <header class="article-header">
    INSERT TEXT HERE
    <h1 title="{{article.title}}" class="article-title">
      {{article.title}}

 
If you want to add some styling to make the text stand out, there's a good method here: How can I add a disclaimer to a Help Center article? It's describing how you'd add a callout to an individual article, but the same method could be applied to the article template in order to make the callout appear in every article. Hope that helps!