fix: use showdown for markdown conversion

packages/core/jest.setup.js

@@ -1,2 +1,7 @@
 var nodeCrypto = require("crypto");
+var jsdom = require("jsdom");
+
+const dom = new jsdom.JSDOM("", {});
+global.window = dom.window;
+global.document = dom.window.document;
 global.crypto = nodeCrypto;