feat: installed mermaid it

eleventy.config.js

@@ -1,6 +1,7 @@
 const markdownIt = require("markdown-it");
 const markdownItContainer = require("markdown-it-container");
 const markdownItFootnote = require("markdown-it-footnote");
+const markdownItMermaid = require('markdown-it-mermaid').default
 const syntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
 const fs = require("fs");
 
@@ -92,6 +93,7 @@ md.use(markdownItContainer, 'details', {
 });
 md.use(markdownItFootnote);
 md.use(markdownItHashtag);
+md.use(markdownItMermaid);
 
 module.exports = (eleventyConfig) => {
   eleventyConfig.addPlugin(syntaxHighlight);