feat: add lazy attribute for img

eleventy.config.js

@@ -14,7 +14,9 @@ let options = {
 };
 let mdfigcaption = require('markdown-it-image-figures');
 let figoptions = {
-  figcaption: true
+  figcaption: true,
+  lazy: true,
+  async: true,
 };
 const mdLib = markdownIt(options).use(mdfigcaption, figoptions);