Add shortcodes for customizing slides, markdown, HTML

exampleSite/content/home/shortcodes/markdown.md

@@ -0,0 +1,30 @@
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+weight = 36
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+
+{{< markdown >}}
+
+## Markdown Shortcode
+
+This markdown is not processed by Hugo, but by Reveal.js itself.
+
+---
+
+## Markdown Shortcode
+
+Many handy slide shortcuts and customizations are possible.
+
+[See them all](https://github.com/hakimel/reveal.js#markdown)
+
+---
+
+<!-- .slide: data-background="blue" -->
+
+For example, an HTML comment can change the background color of a slide.
+
+```
+<!-- .slide: data-background="blue" -->
+```
+
+{{< /markdown >}}
+