Give all embedded live docs examples data-example-id attrs

Refs #11410

docs/_includes/components/thumbnails.html

@@ -5,7 +5,7 @@
 
   <h3 id="thumbnails-default">Default example</h3>
   <p>By default, Bootstrap's thumbnails are designed to showcase linked images with minimal required markup.</p>
-  <div class="bs-example">
+  <div class="bs-example" data-example-id="simple-thumbnails">
     <div class="row">
       <div class="col-xs-6 col-md-3">
         <a href="#" class="thumbnail">
@@ -42,7 +42,7 @@
 
   <h3 id="thumbnails-custom-content">Custom content</h3>
   <p>With a bit of extra markup, it's possible to add any kind of HTML content like headings, paragraphs, or buttons into thumbnails.</p>
-  <div class="bs-example">
+  <div class="bs-example" data-example-id="thumbnails-with-custom-content">
     <div class="row">
       <div class="col-sm-6 col-md-4">
         <div class="thumbnail">