fix: change heading tag of related posts section from h4 to h2 for SEO enhancement (mmistakes#3064)

* Update heading tag from `h4` to `h2`

* Update heading tag from `h4` to `h2`

Author: kulbhushanchand

_layouts/single.html

@@ -65,7 +65,7 @@ <h4 class="page__meta-title">{{ site.data.ui-text[site.locale].meta_label }}</h4
   {% comment %}<!-- only show related on a post page when `related: true` -->{% endcomment %}
   {% if page.id and page.related and site.related_posts.size > 0 %}
     <div class="page__related">
-      <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h4>
+      <h2 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h2>
       <div class="grid__wrapper">
         {% for post in site.related_posts limit:4 %}
           {% include archive-single.html type="grid" %}
@@ -75,7 +75,7 @@ <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label
   {% comment %}<!-- otherwise show recent posts if no related when `related: true` -->{% endcomment %}
   {% elsif page.id and page.related %}
     <div class="page__related">
-      <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h4>
+      <h2 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h2>
       <div class="grid__wrapper">
         {% for post in site.posts limit:4 %}
           {% if post.id == page.id %}

docs/_layouts/single.html

@@ -73,7 +73,7 @@ <h4 class="page__meta-title">{{ site.data.ui-text[site.locale].meta_label }}</h4
               data-ad-format="auto"
               data-full-width-responsive="true"></ins>
       </div>
-      <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h4>
+      <h2 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h2>
       <div class="grid__wrapper">
         {% for post in site.related_posts limit:4 %}
           {% include archive-single.html type="grid" %}
@@ -83,7 +83,7 @@ <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label
   {% comment %}<!-- otherwise show recent posts if no related when `related: true` -->{% endcomment %}
   {% elsif page.id and page.related %}
     <div class="page__related">
-      <h4 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h4>
+      <h2 class="page__related-title">{{ site.data.ui-text[site.locale].related_label | default: "You May Also Enjoy" }}</h2>
       <div class="grid__wrapper">
         {% for post in site.posts limit:4 %}
           {% if post.id == page.id %}