docs: add modified time based on the git commit

config.yml

@@ -2,6 +2,7 @@ languageCode:           "en"
 title:                  "Bootstrap"
 baseURL:                "https://v5.getbootstrap.com"
 enableInlineShortcodes: true
+enableGitInfo:          true
 
 markup:
   goldmark:

site/layouts/partials/social.html

@@ -15,3 +15,13 @@
 <meta property="og:image:type" content="image/png">
 <meta property="og:image:width" content="1000">
 <meta property="og:image:height" content="500">
+{{- $iso8601 := "2006-01-02T15:04:05-07:00" -}}
+{{- if .IsPage }}
+{{ if not .PublishDate.IsZero }}<meta property="article:published_time" {{ .PublishDate.Format $iso8601 | printf "content=%q" | safeHTMLAttr }}>
+{{ else if not .Date.IsZero }}<meta property="article:published_time" {{ .Date.Format $iso8601 | printf "content=%q" | safeHTMLAttr }}>
+{{ end }}
+{{- if not .Lastmod.IsZero }}<meta property="article:modified_time" {{ .Lastmod.Format $iso8601 | printf "content=%q" | safeHTMLAttr }}>{{ end }}
+{{- else }}
+  {{- if not .Date.IsZero }}<meta property="og:updated_time" {{ .Lastmod.Format $iso8601 | printf "content=%q" | safeHTMLAttr }}>
+{{- end }}
+{{- end }}{{/* .IsPage */}}