Install markdown-it-collapsible plugin

eleventy.config.js

@@ -82,6 +82,7 @@ module.exports = function (eleventyConfig) {
         .use(markdownItAnchor, markdownItAnchorOptions)
         .use(require("markdown-it-attrs"))
         .use(require("markdown-it-bracketed-spans"))
+        .use(require("markdown-it-collapsible"))
         .use(require("markdown-it-container"))
         .use(require("markdown-it-deflist"));
 

package.json

@@ -23,6 +23,7 @@
     "markdown-it-anchor": "^8.6.7",
     "markdown-it-attrs": "^4.1.6",
     "markdown-it-bracketed-spans": "^1.0.1",
+    "markdown-it-collapsible": "^2.0.2",
     "markdown-it-container": "^4.0.0",
     "markdown-it-deflist": "^3.0.0",
     "slugify": "^1.6.6"