fix: correct spelling of `panel` (#686)

Co-authored-by: sorin-g <g.sorin94@gmail.com>

_layouts/page.html

@@ -35,7 +35,7 @@ layout: default
     </div>
   </div> <!-- #core-wrapper -->
 
-  <!-- pannel -->
+  <!-- panel -->
   <div id="panel-wrapper" class="col-xl-3 pl-2 text-muted">
 
     <div class="access">
@@ -43,7 +43,7 @@ layout: default
       {% include trending-tags.html %}
     </div>
 
-    {% for _include in layout.pannel_includes %}
+    {% for _include in layout.panel_includes %}
       {% assign _include_path = _include | append: '.html' %}
       {% include {{ _include_path }} %}
     {% endfor %}

_layouts/post.html

@@ -1,7 +1,7 @@
 ---
 layout: page
 refactor: true
-pannel_includes:
+panel_includes:
   - toc
 tail_includes:
   - related-posts

_sass/layout/home.scss

@@ -176,7 +176,7 @@
 
 }
 
-/* Pannel hidden */
+/* Panel hidden */
 @media all and (max-width: 1200px) {
   #post-list {
     padding-right: 0;