Update docs

- Add troubleshooting notes for Chromebook users
- Closes #147

docs/clients-zh.md

@@ -21,6 +21,7 @@
   * [Windows 错误 809](#windows-错误-809)
   * [Windows 错误 628](#windows-错误-628)
   * [Android 6 and 7](#android-6-and-7)
+  * [Chromebook](#chromebook)
   * [其它错误](#其它错误)
   * [额外的步骤](#额外的步骤)
 
@@ -401,6 +402,10 @@ strongswan down myvpn
 
 ![Android VPN workaround](images/vpn-profile-Android.png)
 
+### Chromebook
+
+Chromebook 用户： 如果你无法连接，请尝试 <a href="https://bugs.chromium.org/p/chromium/issues/detail?id=707139#c58" target="_blank">这个解决方案</a>。或者你也可以尝试编辑 VPN 服务器上的 `/etc/ipsec.conf`，找到 `sha2-truncbug=yes` 并将它替换为 `sha2-truncbug=no`。保存修改并运行 `service ipsec restart`。
+
 ### 其它错误
 
 如果你遇到其它错误，请参见以下链接：

docs/clients.md

@@ -21,6 +21,7 @@ An alternative <a href="https://usefulpcguide.com/17318/create-your-own-vpn/" ta
   * [Windows Error 809](#windows-error-809)
   * [Windows Error 628](#windows-error-628)
   * [Android 6 and 7](#android-6-and-7)
+  * [Chromebook](#chromebook)
   * [Other errors](#other-errors)
   * [Additional steps](#additional-steps)
 
@@ -400,6 +401,10 @@ If you are unable to connect using Android 6 (Marshmallow) or 7 (Nougat):
 
 ![Android VPN workaround](images/vpn-profile-Android.png)
 
+### Chromebook
+
+Chromebook users: If you are unable to connect, try <a href="https://bugs.chromium.org/p/chromium/issues/detail?id=707139#c58" target="_blank">this workaround</a>. Alternatively, edit `/etc/ipsec.conf` on the VPN server, find `sha2-truncbug=yes` and replace it with `sha2-truncbug=no`. Save the file and run `service ipsec restart`.
+
 ### Other errors
 
 If you encounter other errors, refer to the links below: