Introduce experimental OpenAPI shortcode

exampleSite/content.en/_index.md

@@ -5,62 +5,42 @@ layout: landing
 <br />
 
 # Hugo Book {anchor=false}
-{{% columns %}}
-- Documentation theme for [Hugo](https://gohugo.io) as simple as plain book.
 
-  Hugo-Book theme is designed to be easy to read, write, navigate and maintain.
-  It is an attempt to create a sustainable web project.
+Documentation theme for [Hugo](https://gohugo.io) as simple as plain book.
 
-  {{<button href="/docs/getting-started/introduction">}}Explore{{</button>}}
+Hugo-Book theme is designed to be easy to read, write, navigate and maintain.  
+It is an attempt to create a sustainable web project.
 
-- ```shell
-  # TL;DR
-  git clone https://github.com/alex-shpak/hugo-book-starter documentation
-  cd documentation
-  git submodule update --init --remote
-  hugo server --minify
-  ```
-{{% /columns %}}
+{{<button href="/docs/getting-started/introduction">}}Explore{{</button>}}
 
+<br />
 <br />
 
 {{% columns %}}
-- {{< card >}}
-  ### Probably fast {anchor=false}
+- ### Probably fast {anchor=false}
   Built on Hugo static site generator. "The world’s fastest framework for building websites".
-  {{< /card >}}
 
-- {{< card >}}
-  ### 50% JS free {anchor=false}
+- ### 50% JS free {anchor=false}
   All important features are working even with JavaScript disabled in the browser, including interactive shortcodes.
-  {{< /card >}}
 
-- {{< card >}}
-  ### Minimalistic {anchor=false}
+- ### Minimalistic {anchor=false}
   For real, it is very minimalistic, black on white. No extra tools are needed to build the site, only Hugo. No heavy JS or CSS frameworks included.
-  {{< /card >}}
 {{% /columns %}}
 
 {{% columns %}}
-- {{< card >}}
-  ### Shortcodes {anchor=false}
+- ### Shortcodes {anchor=false}
   Pretty good shortcodes are included to enhance content:
   [Columns](/docs/content/shortcodes/columns/),
-  [Cards](/docs/content/shortcodes/cards/),
+  [Cards](/docs/content/shortcodes/experimental/cards/),
   [Tabs](/docs/content/shortcodes/tabs/),
-  [Images](/docs/content/shortcodes/images/),
+  [Images](/docs/content/shortcodes/experimental/images/),
   [Asciinema](/docs/content/shortcodes/asciinema/),
   [KaTex](/docs/content/shortcodes/katex/),
   [Mermaid](/docs/content/shortcodes/mermaid/) and others.
-  {{< /card >}}
 
-- {{< card >}}
-  ### Even more {anchor=false}
+- ### Even more {anchor=false}
   Do people actually read these? I thought it was just a visual filler. But there is full-text search and multi-language support.
-  {{< /card >}}
 
-- {{< card >}}
-  ### Made to be extendable {anchor=false}
+- ### Made to be extendable {anchor=false}
   There are multiple points to inject own styles and templates to make it your own.
-  {{< /card >}}
 {{% /columns %}}

exampleSite/content.en/docs/content/shortcodes/experimental/_index.md

@@ -0,0 +1,3 @@
+---
+bookCollapseSection: true
+---

exampleSite/content.en/docs/content/shortcodes/experimental/cards.md

@@ -1,6 +1,6 @@
 # Cards
 
-Content blocks with optional images and links. Often used with [Columns](/docs/content/shortcodes/columns) for grid layouts.
+Content blocks with optional images and links. Often used with [Columns](/docs/content/shortcodes/columns/) for grid layouts.
 
 ## Syntax
 
@@ -18,7 +18,7 @@ Markdown content
   Cards can display an image above the content.
   {{< /card >}}
 
-- {{< card href="/docs/content/shortcodes/cards" >}}
+- {{< card href="/docs/content/shortcodes/experimental/cards/" >}}
   ### With Link {anchor=false}
   When `href` is set, the entire card becomes clickable.
   {{< /card >}}

exampleSite/content.en/docs/content/shortcodes/experimental/openapi.md

@@ -0,0 +1,19 @@
+---
+title: OpenAPI
+---
+
+# OpenAPI
+
+Renders an OpenAPI 3.x specification as a documentation page. Operations are grouped by their first tag.
+
+## Syntax
+
+```tpl
+{{%/* openapi src="spec.json" */%}}
+```
+
+The spec file is loaded via `resources.Get`, so the path is relative to the site's `assets/` directory. JSON and YAML are both supported.
+
+## Example
+
+{{% openapi src="tictactoe.json" %}}