Fix roadmap month appearing twice

In case multiple elements with several dates in one month are inserted,
an additional month layer got added to the roadmap. This changes
ensures, that the month is only displayed once.

_layouts/roadmap.html

@@ -12,6 +12,7 @@
         {%- assign unique_dates = sorted_roadmap | map: "date" | uniq | sort -%}
 
         {%- assign year = "1999" -%}
+        {%- assign month = "None" %}
 
         <section>
             <div class="timeline">
@@ -46,10 +47,16 @@
                 <h1 class="text-center {{ hidden_class }}">{{ newyear }}</h1>
                 {%- endif -%}
 
+                {% assign roadmap_month = date_item | date: "%B" %}
+                {%- if month != roadmap_month -%}
                 <div class="roadmap-month {{ hidden_class }}">
                     <div class="timeline-bubble"></div>
                     <h2>{{ date_item | date: "%B %Y" }}</h2>
                 </div>
+                {%- else -%}
+                <div class="p-3"></div>
+                {%- endif -%}
+                {% assign month = roadmap_month %}
                 <div class="roadmap-item {{ hidden_class }}">
 
                     {%- for roadmap_item in sorted_roadmap_by_date -%}

_roadmap/cloud/2020-10-15.md

 ---
-date: 2020-10-01
+date: 2020-10-15
 title: Tasks in Oct 2020
 service: cloud
 ---