Update docs

docs/ikev2-howto-zh.md

@@ -377,13 +377,25 @@ sudo chmod 600 ikev2vpnca.cer vpnclient.cer vpnclient.key
 
 如果要列出已有的 IKEv2 客户端的名称，运行 [辅助脚本](#使用辅助脚本) 并添加 `--listclients` 选项。使用参数 `-h` 显示使用信息。
 
+```
+sudo ikev2.sh --listclients
+```
+
 ### 添加客户端证书
 
 如果要为更多的 IKEv2 客户端生成证书，只需重新运行 [辅助脚本](#使用辅助脚本)。或者你可以看 [这一小节](#手动在-vpn-服务器上配置-ikev2) 的第 4 步。
 
+```
+sudo ikev2.sh --addclient [client name]
+```
+
 ### 导出已有的客户端的配置
 
-在默认情况下，[IKEv2 辅助脚本](#使用辅助脚本) 在运行后会导出客户端配置。如果之后你想要为一个已有的客户端导出配置，重新运行辅助脚本并选择适当的选项。
+在默认情况下，[IKEv2 辅助脚本](#使用辅助脚本) 在运行后会导出客户端配置。如果之后你想要为一个已有的客户端导出配置，可以运行：
+
+```
+sudo ikev2.sh --exportclient [client name]
+```
 
 ### 删除客户端证书
 
@@ -731,7 +743,7 @@ sudo chmod 600 ikev2vpnca.cer vpnclient.cer vpnclient.key
 
 ### 在导入时提示密码不正确
 
-如果你忘记了客户端配置文件的密码，可以重新 [导出 IKEv2 客户端的配置](#导出已有的客户端的配置)。
+如果你忘记了客户端配置文件的密码，可以查看相同目录下的文件 `vpnclient.p12.password`（如果存在）。或者你也可以重新 [导出 IKEv2 客户端的配置](#导出已有的客户端的配置)。
 
 Ubuntu 18.04 用户在尝试将生成的 `.p12` 文件导入到 Windows 时可能会遇到错误 "输入的密码不正确"。这是由 `NSS` 中的一个问题导致的。更多信息请看 [这里](https://github.com/hwdsl2/setup-ipsec-vpn/issues/414#issuecomment-460495258)。在 2021-01-21 已更新 IKEv2 辅助脚本以自动应用以下解决方法。
 <details>

docs/ikev2-howto.md

@@ -379,13 +379,25 @@ If you get an error when trying to connect, see [Troubleshooting](#troubleshooti
 
 If you want to list the names of existing IKEv2 clients, run the [helper script](#using-helper-scripts) with the `--listclients` option. Use option `-h` to show usage information.
 
+```
+sudo ikev2.sh --listclients
+```
+
 ### Add a client certificate
 
 To generate certificates for additional IKEv2 clients, just run the [helper script](#using-helper-scripts) again. Or you may refer to step 4 in [this section](#manually-set-up-ikev2-on-the-vpn-server).
 
+```
+sudo ikev2.sh --addclient [client name]
+```
+
 ### Export configuration for an existing client
 
-By default, the [IKEv2 helper script](#using-helper-scripts) exports client configuration after running. If later you want to export configuration for an existing client, run the helper script again and select the appropriate option.
+By default, the [IKEv2 helper script](#using-helper-scripts) exports client configuration after running. If later you want to export configuration for an existing client, you may use:
+
+```
+sudo ikev2.sh --exportclient [client name]
+```
 
 ### Delete a client certificate
 
@@ -733,7 +745,7 @@ Before continuing, you **must** restart the IPsec service. The IKEv2 setup on th
 
 ### Incorrect password when trying to import
 
-If you forgot the password for client config files, you may [export configuration for the IKEv2 client](#export-configuration-for-an-existing-client) again.
+If you forgot the password for client config files, check file `vpnclient.p12.password` in the same folder (if exists). Alternatively, you may [export configuration for the IKEv2 client](#export-configuration-for-an-existing-client) again.
 
 Ubuntu 18.04 users may encounter the error "The password you entered is incorrect" when trying to import the generated `.p12` file into Windows. This is due to a bug in `NSS`. Read more [here](https://github.com/hwdsl2/setup-ipsec-vpn/issues/414#issuecomment-460495258). As of 2021-01-21, the IKEv2 helper script was updated to automatically apply the workaround below.
 <details>