Use fontawesome icon for the HTML details element

As discussed in the Mattermost channel, I replaced the default triangle with Fontawesome icons.

_includes/frontpage/title-content.html

 <div>
-    <h1>Helmholtz IT for Science</h1>
-    <details>
-        <summary>
-            HIFIS builds and sustains an excellent IT infrastructure connecting all Helmholtz research fields and
-            centres.
-        </summary>
-        <div>
-            <p>
-                This includes a secure and easy-to-use collaborative environment with efficiently accessible IT services
-                from anywhere.
-                HIFIS further supports Research Software Engineering (RSE) with a high level of quality, visibility and
-                sustainability.
-            </p>
-            <p>
-                The HIFIS clusters develop technologies, processes and policy frameworks for harmonized access to
-                fundamental backbone services, such as Helmholtz AAI, and Helmholtz Cloud services. HIFIS Software also
-                provides education, technology, consulting and community services.
-            </p>
-        </div>
-    </details>
+    <h1>Federated IT for Science</h1>
+    <p>HIFIS ensures an excellent information environment for outstanding research in all Helmholtz research fields.</p>
 </div>
 <div class="services-box">
     <div class="services-title-buttons">