Fix agent-frameworks page displaying as raw code (#672)

Remove erroneous markdown code fence wrappers that were causing the
MDX content to render as a code block instead of proper components.

Co-authored-by: Rachel Lee Nabors <nearestnabors@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: nearestnabors

app/en/guides/agent-frameworks/page.mdx

@@ -1,4 +1,3 @@
-```mdx
 import { PlatformCard } from "@/app/_components/platform-card";
 import { Tabs } from "nextra/components";
 
@@ -72,4 +71,3 @@ These guides are for developers building AI applications who need to connect Arc
     </div>
   </Tabs.Tab>
 </Tabs>
-```