Let's follow the steps to add Font-Awesome icons to our Angular web application:

1. First, we will need to add Font-Awesome's font files and styles to our /src/styles.scss or another global Sass file in our project. Again, we use sass-loader's helpful lookup feature to reference both the font files inside node_modules/font-awesome/fonts/ and then import its Sass styles from node_modules/font-awesome/scss/.

@import "~font-awesome/scss/font-awesome";

2. We will also need to tell font-awesome where it can find the font files required by its styles by providing it with a style path. We will define this before our Font-Awesome import so that this value will override the default variable value inside Font-Awesome's Sass.

$fa-font-path: "~font-awesome/fonts";
@import "~font-awesome/scss/font-awesome";

3. Now that we have font-awesome loaded, we can use its provided styles to start adding icons to our accordion component:

<ngb-accordion activeIds="ngb-panel-0">
  <ngb-panel >
    <template ngbPanelTitle>
      <strong><i class="fa fa-user"></i> Matt DeLucas</strong>
    </template>
    <template ngbPanelContent>
      <ul class="list-unstyled">
        <li><i class="fa fa-newspaper-o"></i> Post 1</li>
        <li><i class="fa fa-newspaper-o"></i> Post 2</li>
        <li><i class="fa fa-newspaper-o"></i> Post 3</li>
      </ul>
    </template>
  </ngb-panel>
  ...

4. We now have a user icon next to our author's name and a newspaper icon next to every blog post under their name.