index.html: Fix liquid syntax

Upgrading from liquid 2.6.1 to 3.0.6 the error got evident

Signed-off-by: Daiane Angolini <angolini@gmail.com>

index.html

@@ -28,7 +28,7 @@ <h1 class="header author-header" itemprop="headline">{{ site.title }}</h1>
               <h2>Latest Articles</h2>
 
               <ul>
-                  {% for post in site.posts | limit: site.post_limit %}
+                  {% for post in site.posts limit: site.post_limit %}
 
                       <li>
                           <a href="{{ post.url | prepend: site.baseurl }}">{{ post.title }}</a>