add latest new section to frontpage

We use a custom override template (jinja) to generate a suitable list of
new items.

Also added first text for announcing our new user docs

docs/index.md

@@ -2,6 +2,7 @@
 hide:
   - navigation
   - toc
+template: "frontpage.html"
 ---
 
 # HPCE User Documentation
@@ -20,3 +21,5 @@ researchers, staff, and external collaborators, such as the Merlin series of
 HPC clusters. Furthermore the HPCE group engages in research activities on
 technologies (data analysis and machine learning technologies) used on these
 systems.
+
+<!-- note that further content is dynamically added via the overrides/frontpage.html template -->