chore: remove irrelevant custom error handler docs (#7143)

packages/docs/architecture/server-middleware.md

@@ -83,26 +83,3 @@ export default {
 +  }
 }
 ```
-## Customize the error handler
-
-The Server Middleware comes with a default error handler that logs errors to the console and sends a generic error response to the client. You can customize this behavior by providing your own error handler function in the `middleware.config.js` file:
-
-```javascript
-module.exports = {
-  integrations: {
-    ct: {
-      location: '@vsf-enterprise/commercetools-api/server',
-      errorHandler: (
-        error: unknown, /** Error thrown by API method */
-        req: Request, /** Express Request object */
-        res: Response /** Express Response object */
-      ) => {
-        res.status(404);
-        res.send('Custom not-found error handler');
-      },
-      configuration: { ... },
-      ...
-    // remaining configuration
-```
-
-Custom error handler are configured per integration, so you can have different error handlers for different integrations.