Upate secret keys: stop using deprecated fields (#2091)

Author: m1kola

source/includes/steps-kind-quick-start.yaml

@@ -104,9 +104,9 @@ content: |
        name: organization-secret
        namespace: mongodb
      stringData:
-       user: <public_key>
-       publicAPIKey: <private_key>
-  
+       publicKey: <public_key>
+       privateKey: <private_key>
+
   For security purposes, |cloud| displays this file only once.
 
 ---