Update sample content with the mark tag

Author: Gerardo Pacheco

Example/Example/SampleContent/content.html

@@ -159,3 +159,9 @@ <h3>Unsupported HTML</h3>
 </table>
 
 <hr/>
+
+<h3>Mark</h3>
+
+<p>Donec ipsum dolor, <mark style="color:#ff0000">tempor sed</mark> bibendum <mark style="color:#1100ff">vita</mark>.</p>
+
+<hr/>

Example/Example/SampleContent/gutenberg.html

@@ -140,3 +140,11 @@ <h2 style="text-align:center">The WordPress of tomorrow</h2>
 <!-- /wp:separator -->
 
 <!-- wp:latest-posts /-->
+
+<!-- wp:separator -->
+<hr class="wp-block-separator" />
+<!-- /wp:separator -->
+
+<!-- wp:paragraph -->
+<p>Donec ipsum dolor, <mark style="color:#ff0000">tempor sed</mark> bibendum <mark style="color:#1100ff">vita</mark>.</p>
+<!-- /wp:paragraph -->