Update markdown-endpoint.mdx

fix /markdown typescript example

Author: kathayl

src/content/docs/browser-rendering/rest-api/markdown-endpoint.mdx

@@ -39,12 +39,12 @@ curl -X 'POST' 'https://api.cloudflare.com/client/v4/accounts/<accountId>/browse
 import Cloudflare from "cloudflare";
 
 const client = new Cloudflare({
-	apiEmail: process.env["CLOUDFLARE_EMAIL"], // This is the default and can be omitted
-	apiKey: process.env["CLOUDFLARE_API_KEY"], // This is the default and can be omitted
+	apiToken: process.env["CLOUDFLARE_API_TOKEN"],
 });
 
 const markdown = await client.browserRendering.markdown.create({
-	account_id: "account_id",
+	account_id: process.env["CLOUDFLARE_ACCOUNT_ID"],
+	url: "https://developers.cloudflare.com/",
 });
 
 console.log(markdown);