add shortcode for collapsable section

content/pages/playground.md

@@ -10,3 +10,13 @@ asciinema: true
 {{< asciinema key="demo" >}}
 
 There should be a asciinema cast above!
+{{< details title="Click to see sample json" >}}
+```json
+{
+  "external_tracker_url": "https://github.com/caddyserver/caddy/issues",
+  "external_tracker_format": "https://github.com/caddyserver/caddy/issues/{index}",
+  "external_tracker_style": "numeric",
+  "external_tracker_regexp_pattern": ""
+}
+```
+{{< /details >}}

layouts/shortcodes/details.html

@@ -0,0 +1,9 @@
+{{- /*
+Template comment syntax: https://hugo.d.balki.me/templates/introduction/#comments
+collapsable section ref: https://stackoverflow.com/a/78475534
+*/ -}}
+
+<details>
+    <summary>{{ .Get "title" | default "Click to expand" | markdownify }}</summary>
+    <div>{{ .Inner | markdownify }}</div>
+</details>