Minor fix

Author: David-Engel

docs/big-data-cluster/deploy-with-kubeadm.md

@@ -55,7 +55,7 @@ On each machine, there are several required prerequisites. In a bash terminal, r
 1. Import the keys and register the repository for Kubernetes.
 
    ```bash
-   curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo sudo tee /etc/apt/trusted.gpg.d/apt-key.gpg
+   curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo sudo tee /etc/apt/trusted.gpg.d/apt-key.asc
    echo 'deb http://apt.kubernetes.io/ kubernetes-xenial main' | sudo tee -a /etc/apt/sources.list.d/kubernetes.list
    ```