By default, page subheaders display “Validated on” (based on lastmod > publishDate) and “Last edited on” (based on git info). Some automatically-generated content, like many IA pages, instead use “Generated on” with the date of the Hugo build.
For automatically-generated content not supported by an underlying Hugo template, like content generated with an external script, use autogenerated to set the subheader.
autogenerated: true