Try this.

Author: SebKrantz

_pkgdown.yml

@@ -90,4 +90,5 @@ articles:
     - introduction
   - title: Dynamic Factor Models - A Very Short Introduction
     desc: Provides a short theoretical overview of dynamics factor models as used in the economics literature
-    href: https://raw.githubusercontent.com/SebKrantz/dfms/main/vignettes/dynamic_factor_models_paper.pdf
+    contents:
+    - url: https://raw.githubusercontent.com/SebKrantz/dfms/main/vignettes/dynamic_factor_models_paper.pdf