add markdown rendering for program

eleventy.config.js

@@ -73,6 +73,30 @@ module.exports = function(eleventyConfig) {
     return value.filter(item => item.page.lang === this.page.lang)
   });
 
+  eleventyConfig.addAsyncFilter('mdInline', async function(value) {
+    // TODO replace with ESM import once we switch to Eleventy v3
+    const md = (await import('markdown-it/index.mjs')).default();
+
+    // customize link rendering
+    md.renderer.rules.link_open = function (tokens, idx, options, env, self) {
+      const href = tokens[idx].attrGet('href');
+
+      if (href.startsWith('http')) {
+        tokens[idx].attrSet('target', '_blank');
+        tokens[idx].attrSet('rel', 'noreferrer');
+      } else {
+        const newHref = eleventyConfig.javascriptFunctions.locale_url(href);
+        tokens[idx].attrSet('href', newHref);
+      }
+
+      tokens[idx].attrSet('class', 'link');
+
+      return self.renderToken(tokens, idx, options);
+    };
+
+    return md.renderInline(value);
+  });
+
   // copy aileron font
   eleventyConfig.addPassthroughCopy({'./submodules/aileron/fonts/*.(ttf|woff|woff2)': 'fonts'})
   eleventyConfig.addPassthroughCopy({'./submodules/aileron/aileron.lite.min.css': 'aileron.lite.min.css'})