Fix cURL command for disabling v1 API (#154)

Signed-off-by: Andrea <[email protected]>

Author: andrea-hw

docs/v2/system.mdx

@@ -166,7 +166,7 @@ curl https://<IP ADDRESS>/api/system --insecure \
   -X PUT \
   -H "Authorization: Bearer <TOKEN>" \
   -H "X-Api-Version: 2" \
-  -d '{"v1_api_enabled": false}'
+  -d '{"api_v1_enabled": false}'
 ```
 
 ```http title="Response"