diff --git a/_includes/callout.html b/_includes/callout.html
index 8ee72de99841..ff9450dc44f8 100644
--- a/_includes/callout.html
+++ b/_includes/callout.html
@@ -1,5 +1,9 @@
-{% comment %} allowed: info danger warning {% endcomment %}
-{% assign css_class = include.type | default: "info" %}
+{%- comment -%}
+Usage: {% include callout.html content=callout type="type" %},
+where content is a capture with the content
+and type is one of: info (default), danger, warning
+{%- endcomment -%}
+{%- assign css_class = include.type | default: "info" -%}
 <div class="bd-callout bd-callout-{{ css_class }}">
-  {{ include.content | markdownify }}
+  {{- include.content | markdownify -}}
 </div>