fixing series demo links

_includes/custom/getting_started_series_next.html

@@ -4,7 +4,7 @@
     {% if p.series == "Getting Started" %}
     {% assign nextTopic = page.weight | plus: "1"  %}
     {% if p.weight == nextTopic  %}
-    <a href="{{p.url}}"><button type="button" class="btn btn-primary">Next: {{p.title}}</button></a>
+    <a href="{{p.url | remove: "/"}}"><button type="button" class="btn btn-primary">Next: {{p.title}}</button></a>
     {% endif %}
     {% endif %}
     {% endfor %}