feat: add whatsnew archetype

umh.docs.umh.app/archetypes/whatsnew.md

@@ -0,0 +1,18 @@
+---
+title: "What's New in Version {{ .Name }}"
+content_type: whatsnew
+description: |
+    This section contains information about the new features and changes in the
+    United Manufacturing Hub introduced in version {{ .Name }}.
+weight: -1
+---
+
+<!-- overview -->
+
+Welcome to United Manufacturing Hub version {{ .Name }}!
+<!-- insert a one-liner about the release here -->
+
+For a complete list of changes, refer to the
+[release notes](/docs/releases/notes/{{ .Name }}/).
+
+<!-- body -->