Revise notes about Raft Engine (#7995)

tikv-configuration-file.md

@@ -1323,9 +1323,9 @@ Configuration items related to `raftdb`
 Configuration items related to Raft Engine.
 
 > **Note:**
-> 
-> - When you enable Raft Engine for the first time, you need to wait tens of seconds because TiKV switches to the data format of Raft Engine from the one of RocksDB.
-> - The data format of Raft Engine in TiDB v5.4.0 is not compatible with previous versions. Therefore, when downgrading a TiDB cluster from v5.4.0 to earlier versions, you need to disable Raft Engine (by setting the value of `enable` to `false`) **before** downgrading and restart TiKV to make the configuration take effect. Otherwise, you cannot start the downgraded cluster.
+>
+> - When you enable Raft Engine for the first time, TiKV transfers its data from RocksDB to Raft Engine. Therefore, you need to wait extra tens of seconds for TiKV to start.
+> - The data format of Raft Engine in TiDB v5.4.0 is not compatible with earlier TiDB versions. Therefore, if you need to downgrade a TiDB cluster from v5.4.0 to an earlier version, **before** downgrading, disable Raft Engine by setting `enable` to `false` and restart TiKV for the configuration to take effect.
 
 ### `enable`