TiDB binlog: update descriptions about commit ts and passoword (#5986) (

#6036)

tidb-binlog/deploy-tidb-binlog.md

@@ -330,9 +330,9 @@ The following part shows how to use Pump and Drainer based on the nodes above.
         [syncer.to]
         host = "192.168.0.13"
         user = "root"
+        # If you do not want to set a cleartext `password` in the configuration file, you can create `encrypted_password` using `./binlogctl -cmd encrypt -text string`.
+        # When you have created an `encrypted_password` that is not empty, the `password` above will be ignored, because `encrypted_password` and `password` cannot take effect at the same time.
         password = ""
-        # `encrypted_password` is encrypted using `./binlogctl -cmd encrypt -text string`.
-        # When `encrypted_password` is not empty, the `password` above will be ignored.
         encrypted_password = ""
         port = 3306
 

tidb-binlog/tidb-binlog-configuration-file.md

@@ -172,8 +172,12 @@ This section introduces the configuration items of Drainer. For the example of a
 
 ### initial-commit-ts
 
-* Specifies from which commit timestamp the replication task starts. This configuration is only applicable to the Drainer node that starts replication for the first time. If a checkpoint already exists downstream, the replication will be performed according to the time recorded in the checkpoint.
-* Default value: `-1`. Drainer will get a new timestamp from PD as the starting time.
+* Specifies from which commit timestamp of the transaction the replication process starts. This configuration is applicable only to the Drainer node that is in the replication process for the first time. If a checkpoint already exists in the downstream, the replication will be performed according to the time recorded in the checkpoint.
+* commit ts (commit timestamp) is a specific point in time for [transaction](/transaction-overview.md#transactions) commits in TiDB. It is a globally unique and increasing timestamp from PD as the unique ID of the current transaction. You can get the `initial-commit-ts` configuration in the following typical ways:
+    - If BR is used, you can get `initial-commit-ts` from the backup TS recorded in the metadata backed up by BR (backupmeta).
+    - If Dumpling is used, you can get `initial-commit-ts` from the Pos recorded in the metadata backed up by Dumpling (metadata),
+    - If PD Control is used, `initial-commit-ts` is in the output of the `tso` command.
+* Default value: `-1`. Drainer will get a new timestamp from PD as the starting time, which means that the replication process starts from the current time.
 
 ### synced-check-time