Update hello-minikube.md (kubernetes#10440)

Added `shell` highlighting.

content/en/docs/tutorials/hello-minikube.md

@@ -37,13 +37,13 @@ Minikube provides a simple way of running Kubernetes on your local machine for f
  {{< note >}}
  **Note:** If you see the following Homebrew error when you run `brew update` after you update your computer to macOS 10.13:
 
- ```
+ ```shell
  Error: /usr/local is not writable. You should change the ownership
  and permissions of /usr/local back to your user account:
  sudo chown -R $(whoami) /usr/local
  ```
  You can resolve the issue by reinstalling Homebrew:
- ```
+ ```shell
  /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
  ```
  {{< /note >}}