docs: add instruction for omitting scope in oco git configuration

Author: Rasic2

docs/source/development/git.md

@@ -561,6 +561,7 @@ oco config set OCO_API_KEY=xxx
 ```bash
 oco config set OCO_GITPUSH=false # 关闭自动 push
 oco config set OCO_ONE_LINE_COMMIT=true # 单行 commit
+ oco config set OCO_OMIT_SCOPE=true # 省略 scope
 ```
 
 4. 使用 oco 命令生成 commit