adds page last modified above header

_layouts/default.html

@@ -59,6 +59,9 @@ layout: table_wrappers
             {% endif %}
           {% endunless %}
           <div id="main-content" class="page-content" role="main">
+            {% if page.last_modified_date %}
+            <p class="text-small text-grey-dk-000 mb-0">Page last modified: {{ page.last_modified_date | date: "%Y-%m-%d %H:%M" }}</p>
+            {% endif %}
             {% if site.heading_anchors != false %}
               {% include vendor/anchor_headings.html html=content  beforeHeading = "true" anchorBody="<svg class=\"d-inline-block v-align-middle\" viewBox=\"0 0 16 16\" version=\"1.1\" width=\"18\" height=\"18\" aria-hidden=\"true\"><path fill-rule=\"evenodd\" d=\"M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z\"></path></svg>" anchorClass="anchor-heading" %}
             {% else %}