{% for post in site.posts %}
{% unless post.next %}
{{ post.date | date: '%B' }}
{% else %}
{% capture month %}{{ post.date | date: '%B' }}{% endcapture %}
{% capture nmonth %}{{ post.next.date | date: '%B' }}{% endcapture %}
{% if month != nmonth %}
{{ post.date | date: '%B' }}
{% endif %}
{% endunless %}
- {{ post.date | date:"%d." }} {{ post.title }}
{% endfor %}