Update cloudformation-template-ipsec (#850)

* Update cloudformation-template-ipsec

- Add "CreationPolicy" to notify the user when the setup script succeeds on the virtual machine. The stack fails if the script fails.
- The timeout is 10 minutes.
- This feature is to be tested on Debian(s). I have personally tested it on Ubuntu20.

* Update README.md

- Remove the notice no longer needed. (The stack will be flagged as CREATE_COMPLETE only when the script succeeds on the VM.)

* Update README-zh.md

- 移除没用的贴士。堆栈将会自动检查脚本是否成功执行。

aws/README.md

@@ -31,9 +31,7 @@ Click the icon below to start:
 
 <a href="https://console.aws.amazon.com/cloudformation/home#/stacks/new" target="_blank"><img src="cloudformation-launch-stack-button.png" alt="Launch stack" height="34px"></a>
 
-You may choose an AWS region using the selector to the right of your account information on the navigation bar. After the stack is successfully created, click the **Outputs** tab to view your VPN login details. Then continue to [Next steps: Configure VPN Clients](../README.md#next-steps).
-
-> **Note:** You will need to wait at least 5 minutes after the stack shows **CREATE_COMPLETE**, before you can connect to the server with a VPN client. This is to allow time for the VPN setup to complete.
+You may choose an AWS region using the selector to the right of your account information on the navigation bar. As soon as the stack's status turns **"CREATE_COMPLETE"**, you are ready to connect to the VPN server. Click the **Outputs** tab to view your VPN login details. Then continue to [Next steps: Configure VPN Clients](../README.md#next-steps).
 
 ## FAQs