Fixed the default value of a config property

Author: liyinan926

docs/running-on-kubernetes.md

@@ -656,7 +656,7 @@ specific to Spark on Kubernetes.
 </tr>
 <tr>
   <td><code>spark.kubernetes.executor.secrets.[SecretName]</code></td>
-  <td>5</td>
+  <td>(none)</td>
   <td>
    Add the <a href="https://kubernetes.io/docs/concepts/configuration/secret/">Kubernetes Secret</a> named <code>SecretName</code> to the executor pod on the path specified in the value. For example,
    <code>spark.kubernetes.executor.secrets.spark-secret=/etc/secrets</code>. Note that if an init-container is used,