help with the article.html file

jonathan.html

{% if post.external-url %} <!-- this block gets run if the external-url attribute is present -->
    <h1 class="entry-title external">
        <a href="{{ post.external-url }}"> <!-- NOTE: see that the href is to the post's external-url attribute? that's what's needed for the links to work. -->
            <!-- on my site, I include "[link]" here -->
            {% if site.titlecase %}
                {{ post.title | titlecase }}
            {% else %}
                {{ post.title }}
            {% endif %}
        </a>
    </h1>
{% else %} <!-- if the external-url attribute is not present, this code gets run -->
    <h1 class="entry-title">
        <a href="{{ root_url }}{{ post.url }}">
            {% if site.titlecase %}
                {{ post.title | titlecase }}
            {% else %}
                {{ post.title }}
            {% endif %}
        </a>
    </h1>
{% endif %}