docs: use the native-language label for the cross-language readme link

English readme links the Chinese version as 中文; the Chinese readme already links the English version as English. Both readmes stay version-free and section-synchronized (14 matching sections).

Co-authored-by: deepagent-code <deepagent-code@deepagent.ltd>

Author: deepagent-ai

README.md

@@ -10,7 +10,7 @@
 
 <p align="center">
   <a href="README.md">English</a> |
-  <a href="README.zh.md">简体中文</a> |
+  <a href="README.zh.md">中文</a> |
   <a href="https://github.com/deepagent-ltd/deepagent-code-enterprise">Enterprise</a>
 </p>