Updated heading nesting

Author: ericwbailey

partials/section.embedded.hbs

@@ -1,17 +1,17 @@
 <section id="section__embedded" aria-labelledby="title__embedded"><!-- Start of #section__embedded -->
     <h2 id="title__embedded">Embedded</h2>
 
-    <h2 id="subsection__image">Image</h2><!-- Start of #subsection__image -->
+    <h3 id="subsection__image">Image</h3><!-- Start of #subsection__image -->
     <img
         src="http://placehold.it/600x400?text=Image+Example"
         alt="Image Exmaple" /><!-- End of #subsection__image -->
 
-    <h2 id="subsection__broken-image">Broken Image</h2><!-- Start of #subsection__broken-image -->
+    <h3 id="subsection__broken-image">Broken Image</h3><!-- Start of #subsection__broken-image -->
     <img
         src="nope"
         alt="Broken Image" /><!-- End of #subsection__broken-image -->
 
-    <h2 id="subsection__figure-with-caption">Figure with Caption</h2><!-- Start of #subsection__figure-with-caption -->
+    <h3 id="subsection__figure-with-caption">Figure with Caption</h3><!-- Start of #subsection__figure-with-caption -->
     <figure>
         <img
             src="http://placehold.it/400x250?text=Figure+Example"
@@ -21,7 +21,7 @@
         </figcaption>
     </figure><!-- End of #subsection__figure-with-caption -->
 
-    <h2 id="subsection__inline-svg">Inline SVG</h2><!-- Start of #subsection__inline-svg -->
+    <h3 id="subsection__inline-svg">Inline SVG</h3><!-- Start of #subsection__inline-svg -->
     <figure>
         <svg
             aria-labelledby="svg__title svg__description"
@@ -52,7 +52,7 @@
         </li>
     </ul>
 
-    <h2 id="subsection__picture">Picture</h2><!-- Start of #subsection__picture -->
+    <h3 id="subsection__picture">Picture</h3><!-- Start of #subsection__picture -->
     <picture>
         <source
             media="(min-width: 40em)"
@@ -66,7 +66,7 @@
             alt="Picture Element" />
     </picture><!-- End of #subsection__picture -->
 
-    <h2 id="subsection__image-with-srcset-and-sizes">Image with Srcset and Sizes</h2><!-- Start of #subsection__image-with-srcset-and-sizes -->
+    <h3 id="subsection__image-with-srcset-and-sizes">Image with Srcset and Sizes</h3><!-- Start of #subsection__image-with-srcset-and-sizes -->
     <img
         srcset="http://placehold.it/1024x768/7ED321/ffffff/?text=Large 1024w,
                 http://placehold.it/1024x768/F5A623/ffffff/?text=Medium 640w,
@@ -75,14 +75,14 @@
         src="http://placehold.it/600x400?text=Img+Fallback"
         alt="Image with Srcset and Sizes Example" /><!-- End of #subsection__image-with-srcset-and-sizes -->
 
-    <h2 id="subsection__iframe">Iframe</h2><!-- Start of #subsection__iframe -->
+    <h3 id="subsection__iframe">Iframe</h3><!-- Start of #subsection__iframe -->
     <iframe
         src="about:blank"
         title="about:blank"
         name="iframe"><!-- End of #subsection__iframe -->
     </iframe>
 
-    <h2 id="subsection__audio">Audio</h2><!-- Start of #subsection__audio -->
+    <h3 id="subsection__audio">Audio</h3><!-- Start of #subsection__audio -->
     <audio controls>
         <source
             src="http://www.noiseaddicts.com/samples_1w72b820/4353.mp3"
@@ -102,7 +102,7 @@
         Please <a rel="external noopener" href="http://browsehappy.com/">consider upgrading your browser</a> or <a download href="http://www.noiseaddicts.com/samples_1w72b820/4353.mp3">download a file</a> for offline listening.
     </audio><!-- End of #subsection__audio -->
 
-    <h2 id="subsection__video">Video</h2><!-- Start of #subsection__video -->
+    <h3 id="subsection__video">Video</h3><!-- Start of #subsection__video -->
     <video
         controls
         poster="http://placehold.it/854x480?text=Video+Poster">
@@ -129,7 +129,7 @@
         <small>Accessibility errors concerning the video's missing audio description should go away once the <code>&lt;track&gt;</code>'s source is linked to a valid caption file.</small>
     </p>
 
-    <h2 id="subsection__object">Object</h2><!-- Start of #subsection__object -->
+    <h3 id="subsection__object">Object</h3><!-- Start of #subsection__object -->
     <object>
         <param
             name="movie"
@@ -155,7 +155,7 @@
         Please <a rel="external noopener" href="http://browsehappy.com/">consider upgrading your browser</a> or <a rel="external noopener" href="https://www.youtube.com/watch?v=pDHzK3Xe7Yw">view the video on YouTube</a>.
     </object><!-- End of #subsection__object -->
 
-    <h2 id="subsection__canvas">Canvas</h2><!-- Start of #subsection__canvas -->
+    <h3 id="subsection__canvas">Canvas</h3><!-- Start of #subsection__canvas -->
     <canvas
         id="myCanvas"
         width="400"