Fix typo

Author: beebeb

README.md

@@ -4,7 +4,7 @@
 1. [单体架构与微服务架构差异](./Course1:%20What%20is%20Microservice/index.md)
 2. [拆分单体架构策略](./Course2:%20Decompose%20monolithic%20system/index.md)
 3. [微服务集成]((./../Course3:%20Message%20queue/index.md))
-4. [分布式事务管理](./Course4:%20Manage%20transations%20using%20Saga/index.md))
+4. [分布式事务管理](./Course4:%20Manage%20transactions%20using%20Saga/index.md)
 5. [以为微服务方式实现业务功能](./Course5:%20Implementing%20business%20logic/index.md)
 6. [命令查询职责分离以及API网关](./Course6:%20CQRS/index.md)
 8. 其它（测试微服务， 微服务部署， 重构）