If I check official documentation, I can see a property called HTML:
Name | Type | default | Description
---------------------------------
Just as normal, using data-original-title:
Html:
Visible text
Javascript:
$("[rel=tooltip]").tooltip({html:true});
The html parameter specifies how the tooltip text should be turned into DOM elements. By default Html code is escaped in tooltips to prevent XSS attacks. Say you display a username on your site and you show a small bio in a tooltip. If the html code isn't escaped and the user can edit the bio themselves they could inject malicious code.