date-modified is html only option (#196)

Author: OriolAbril

_quarto.yml

@@ -32,8 +32,7 @@ book:
           postal-code: 15108
     - name: ArviZ-devs
       url: https://github.com/arviz-devs
-  date: 2025-04-02
-  date-modified: today
+  date: today
   favicon: favicon.ico
 
   chapters:
@@ -74,6 +73,8 @@ book:
 
 format:
   html:
+    date: 2025-04-02
+    date-modified: today
     toc: true
     code-line-numbers: true
     number-sections: true