Apply suggestions from code review

Author: Oreoxmt

en/upgrade-a-tidb-cluster.md

@@ -25,7 +25,7 @@ During the rolling update, TiDB Operator automatically completes Leader transfer
 ## Preparations before upgrade
 
 1. Refer to the [upgrade caveat](https://docs.pingcap.com/tidb/dev/upgrade-tidb-using-tiup#upgrade-caveat) to learn about the precautions. Note that all TiDB versions, including patch versions, currently do not support downgrade or rollback after upgrade.
-2. Refer to [TiDB release notes](https://docs.pingcap.com/tidb/stable/release-notes) to learn about the compatibility changes in each intermediate version. If any changes affect your upgrade, take appropriate measures.
+2. Refer to [TiDB release notes](https://docs.pingcap.com/releases/tidb-self-managed/) to learn about the compatibility changes in each intermediate version. If any changes affect your upgrade, take appropriate measures.
 
     For example, if you upgrade from TiDB v6.4.0 to v6.5.2, you need to check the compatibility changes in the following versions:
 

zh/upgrade-a-tidb-cluster.md

@@ -23,7 +23,7 @@ Kubernetes 提供了[滚动更新功能](https://kubernetes.io/docs/tutorials/ku
 ## 升级前准备
 
 1. 查阅[升级兼容性说明](https://docs.pingcap.com/zh/tidb/dev/upgrade-tidb-using-tiup#1-升级兼容性说明)，了解升级的注意事项。注意包括补丁版本在内的所有 TiDB 版本目前暂不支持降级或升级后回退。
-2. 查阅 [TiDB release notes](https://docs.pingcap.com/zh/tidb/stable/release-notes) 中各中间版本的兼容性变更。如果有任何变更影响到了你的升级，请采取相应的措施。
+2. 查阅 [TiDB release notes](https://docs.pingcap.com/zh/releases/tidb-self-managed/) 中各中间版本的兼容性变更。如果有任何变更影响到了你的升级，请采取相应的措施。
 
     例如，从 TiDB v6.4.0 升级至 v6.5.2 时，需查阅以下各版本的兼容性变更：