Add underline styling to article titles

Author: Niangh-Ciang

Wireframe/index.html

@@ -18,7 +18,9 @@ <h1>Understanding Project Structure</h1>
           src="https://docs.github.com/assets/cb-55933/images/help/repository/readme-links.png"
           alt="readme file example"
         />
-        <h2>What is the purpose of a README file?</h2>
+        <h2>
+          What is the purpose of a <span class="underline">README file</span>?
+        </h2>
         <p>
           A README file is the foundational documentation for a software,
           dataset, or coding project. It serves as a project's "front door,"
@@ -37,7 +39,9 @@ <h2>What is the purpose of a README file?</h2>
           src="https://cdn-images.visual-paradigm.com/handbooks/agile-handbook/wireframe/02-newspaper-site-wireframe-example.png"
           alt="Wireframe sketch"
         />
-        <h2>What is the purpose of a wireframe?</h2>
+        <h2>
+          What is the purpose of a <span class="underline">wireframe</span>?
+        </h2>
         <p>
           The purpose of a wireframe is to act as a blueprint for a website or
           app. It provides a basic, stripped-down visual guide that outlines
@@ -56,7 +60,7 @@ <h2>What is the purpose of a wireframe?</h2>
           src="https://miro.medium.com/1*K9scAx1Ezd-KJFabaYseCw.jpeg"
           alt="Branch diagram"
         />
-        <h2>What is a branch in Git?</h2>
+        <h2>What is a <span class="underline">branch</span> in Git?</h2>
         <p>
           A branch in Git is simply a lightweight movable pointer to one of
           these commits. The default branch name in Git is master . As you start