Rename "mainland China" to "China"

README.md

@@ -423,7 +423,7 @@ git clone --depth=1 https://github.com/romkatv/powerlevel10k.git ~/powerlevel10k
 echo 'source ~/powerlevel10k/powerlevel10k.zsh-theme' >>~/.zshrc
 ```
 
-Users in mainland China can use the official mirror on gitee.com for faster download.<br>
+Users in China can use the official mirror on gitee.com for faster download.<br>
 中国大陆用户可以使用 gitee.com 上的官方镜像加速下载.
 
 ```zsh
@@ -441,7 +441,7 @@ make sure to disable the current theme in your plugin manager. See
     ```zsh
     git clone --depth=1 https://github.com/romkatv/powerlevel10k.git ${ZSH_CUSTOM:-$HOME/.oh-my-zsh/custom}/themes/powerlevel10k
     ```
-    Users in mainland China can use the official mirror on gitee.com for faster download.<br>
+    Users in China can use the official mirror on gitee.com for faster download.<br>
     中国大陆用户可以使用 gitee.com 上的官方镜像加速下载.
 
     ```zsh