Fix a typo

Author: mrmrs

docs/themes/opacity/index.html

@@ -111,13 +111,12 @@ <h1 class="f4 ttu tracked fw6">Next</h1>
   </div>
   <div class="mt5">
     <h1 class="f4 ttu tracked fw6">Reference</h1>
-    <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img" class="db link fw6 blue dim">MDN - Images HTML</a>
-    <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/image" class="db link fw6 blue dim">MDN - Images CSS</a>
+    <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/opacity" class="db link fw6 blue dim">MDN - Opacity CSS</a>
   </div>
 </div>
       <section class="bg-near-white black-70 pt4 pb5">
 <header class="ph3 ph5-ns pt4">
-        <kbd class="yellow">src/_images.css</kbd>
+        <kbd class="yellow">src/_opacity.css</kbd>
 </header>
 <pre class="ph3 ph5-ns">
 <code class="code" style="font-size: .75rem;">

src/templates/docs/opacity/index.html

@@ -84,13 +84,12 @@ <h1 class="f4 ttu tracked fw6">Next</h1>
   </div>
   <div class="mt5">
     <h1 class="f4 ttu tracked fw6">Reference</h1>
-    <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img" class="db link fw6 blue dim">MDN - Images HTML</a>
-    <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/image" class="db link fw6 blue dim">MDN - Images CSS</a>
+    <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/opacity" class="db link fw6 blue dim">MDN - Opacity CSS</a>
   </div>
 </div>
       <section class="bg-near-white black-70 pt4 pb5">
 <header class="ph3 ph5-ns pt4">
-        <kbd class="yellow">src/_images.css</kbd>
+        <kbd class="yellow">src/_opacity.css</kbd>
 </header>
 <pre class="ph3 ph5-ns">
 <code class="code" style="font-size: .75rem;">