add tooltip to image bootstrap code example

Example 1: bootstrap 4 tooltip

<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="top" title="Tooltip on top">
  Tooltip on top
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="right" title="Tooltip on right">
  Tooltip on right
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="bottom" title="Tooltip on bottom">
  Tooltip on bottom
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-placement="left" title="Tooltip on left">
  Tooltip on left
</button>
<button type="button" class="btn btn-secondary" data-toggle="tooltip" data-html="true" title="<em>Tooltip</em> <u>with</u> <b>HTML</b>">
  Tooltip with HTML
</button>

Example 2: bootsrap button popup text on hover

<!-- HTML to write -->
<a href="#" data-toggle="tooltip" title="Some tooltip text!">Hover over me</a>

<!-- Generated markup by the plugin -->
<div class="tooltip bs-tooltip-top" role="tooltip">
  <div class="arrow"></div>
  <div class="tooltip-inner">
    Some tooltip text!
  </div>
</div>