fix: accessibility issue with reference page

Author: Ashwin Kumar

src/pages/[platform]/reference/amplify_outputs/index.mdx

@@ -127,6 +127,6 @@ Amplify.configure({
 
 The Amplify outputs file is defined using a JSON schema. You can find this schema in the [`aws-amplify/amplify-backend` repository](https://github.com/aws-amplify/amplify-backend/blob/main/packages/client-config/src/client-config-schema/schema_v1.json).
 
-<pre><code style={{ maxWidth: "100%", overflowX: "scroll" }}>
+<pre><code tabIndex="0" style={{ maxWidth: "100%", overflowX: "scroll" }}>
 {JSON.stringify(schema, null, 2)}
 </code></pre>