如何在Twitter Bootstrap中将帮助文本添加到输入上方而不是下方

<div class="container">
  <div class="row">
    <div class="col-md-6">
      <div class="form-group">
       <label for="exampleInputEmail1">Email address</label>
       <input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
       <small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone else.</small>
      </div>
    </div>
  </div>
</div>

<div class="container">
  <div class="row">
    <div class="col-md-6">
      <div class="form-group">
       <label for="exampleInputEmail1">Email address</label>
       <input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
        <div class="invalid-tooltip">
          We'll never share your email with anyone else.
        </div>
      </div>
    </div>
  </div>
</div>

// 显示工具提示
document.getElementById('exampleInputEmail1').classList.add('is-invalid');

// 隐藏工具提示
document.getElementById('exampleInputEmail1').classList.remove('is-invalid');