bootstrap-将头像放在标题最右侧的下拉列表中

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Logo</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav ml-auto">
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          <img src="avatar.jpg" alt="Avatar" class="avatar"> <!-- 头像图片 -->
        </a>
        <div class="dropdown-menu dropdown-menu-right" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">个人信息</a>
          <a class="dropdown-item" href="#">设置</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">退出</a>
        </div>
      </li>
    </ul>
  </div>
</nav>