Adding a horizontal rule below the joined date. (#74)

src/components/ProfilePage.jsx

@@ -109,6 +109,7 @@ export class ProfilePage extends React.Component {
       <React.Fragment>
         <h1 className="h2 mb-0">{username}</h1>
         <DateJoined date={dateJoined} />
+        <hr className="d-none d-md-block" />
       </React.Fragment>
     );