message: docs(datepicker): fix description at placement datepicker demo by changing tag
diff: <div class="row">
  <div class="col-xs-12 col-12 col-sm-6 col-md-3 form-group">
  - <label>The datepicker's placement is right</label>
  + <p>The datepicker's placement is right</p>
  <input class="form-control"
  placeholder="Datepicker"
  bsDatepicker
  placement="right">
  </div>
  <div class="col-xs-12 col-12 col-sm-6 col-md-3 form-group">
  - <label>The datepicker's placement is top</label>
  + <p>The datepicker's placement is top</p>
  <input class="form-control"
  placeholder="Datepicker"
  bsDatepicker
  placement="top">
  </div>
  <div class="col-xs-12 col-12 col-sm-6 col-md-3 form-group">
  - <label>The datepicker's placement is bottom</label>
  + <p>The datepicker's placement is bottom</p>
  <input class="form-control"
  placeholder="Datepicker"
  bsDatepicker
  placement="bottom">
  </div>
  <div class="col-xs-12 col-12 col-sm-6 col-md-3 form-group">
  - <label>The datepicker's placement is left</label>
  + <p>The datepicker's placement is left</p>
  <input class="form-control"
  placeholder="Datepicker"
  bsDatepicker
  