Fix document error about 'make trans-copy'

Author: dlintw

docs/content/development/hacking-on-gitea.en-us.md

@@ -334,7 +334,7 @@ can test your changes to ensure that they pass continuous integration using:
 
 ```bash
 # from the docs directory within Gitea
-make trans-copy clean build
+make docs clean build
 ```
 
 You will require a copy of [Hugo](https://gohugo.io/) to run this task. Please

docs/content/development/hacking-on-gitea.zh-cn.md

@@ -308,7 +308,7 @@ TAGS="bindata sqlite sqlite_unlock_notify" make build test-sqlite
 
 ```bash
 # 来自 Gitea 中的 docs 目录
-make trans-copy clean build
+make docs clean build
 ```
 
 运行此任务依赖于 [Hugo](https://gohugo.io/)。请注意：这可能会生成一些未跟踪的 Git 对象，