fix(ins): fix indentation

Author: bene2k1

pages/instances/api-cli/attaching-a-volume.mdx

@@ -24,7 +24,7 @@ dates:
 
 1. Query the current volumes of the Instance.
     ```
-  curl -X GET \
+    curl -X GET \
     -H "X-Auth-Token: $SCW_SECRET_KEY" \
     "https://api.scaleway.com/instance/v1/zones/{zone}/servers/{server_id}"
     ```