dm: update doc for relay log (#13433)

Author: ran-huang

dm/dm-export-import-config.md

@@ -69,7 +69,7 @@ config import [--dir directory]
 
 > **Note:**
 >
-> For clusters later than v2.0.2, currently, it is not supported to automatically import the configuration related to relay worker. You can use `start-relay` command to manually [start relay log](/dm/relay-log.md#start-and-stop-the-relay-log-feature).
+> For clusters later than v2.0.2, currently, it is not supported to automatically import the configuration related to relay worker. You can use `start-relay` command to manually [start relay log](/dm/relay-log.md#enable-and-disable-relay-log).
 
 ### Parameter explanation
 

dm/dm-handle-alerts.md

@@ -91,7 +91,7 @@ This document introduces how to deal with the alert information in DM.
     You can take the following methods to handle the alert:
 
     - Delete unwanted data manually to increase free disk space.
-    - Reconfigure the [automatic data purge strategy of the relay log](/dm/relay-log.md#automatic-data-purge) or [purge data manually](/dm/relay-log.md#manual-data-purge).
+    - Reconfigure the [automatic data purge strategy of the relay log](/dm/relay-log.md#automatic-purge) or [purge data manually](/dm/relay-log.md#manual-purge).
     - Execute the command `pause-relay` to pause the relay log pulling process. After there is enough free disk space, resume the process by running the command `resume-relay`. Note that you must not purge upstream binlog files that have not been pulled after the relay log pulling process is paused.
 
 ### `DM_relay_log_data_corruption`

dm/dm-source-configuration-file.md

@@ -70,9 +70,9 @@ This section describes each configuration parameter in the configuration file.
 | :------------ | :--------------------------------------- |
 | `source-id` | Represents a MySQL instance ID. |
 | `enable-gtid` | Determines whether to pull binlog from the upstream using GTID. The default value is `false`. In general, you do not need to configure `enable-gtid` manually. However, if GTID is enabled in the upstream database, and the primary/secondary switch is required, you need to set `enable-gtid` to `true`. |
-| `enable-relay` | Determines whether to enable the relay log feature. The default value is `false`. Since DM v2.0.2, this configuration item is deprecated. To [enable the relay log feature](/dm/relay-log.md#start-and-stop-the-relay-log-feature), use the `start-relay` command instead. |
-| `relay-binlog-name` | Specifies the file name from which DM-worker starts to pull the binlog. For example, `"mysql-bin.000002"`. It only works when `enable_gtid` is `false`. If this parameter is not specified, DM-worker will pull the binlogs starting from the latest one. |
-| `relay-binlog-gtid` | Specifies the GTID from which DM-worker starts to pull the binlog. For example, `"e9a1fc22-ec08-11e9-b2ac-0242ac110003:1-7849"`. It only works when `enable_gtid` is `true`. If this parameter is not specified, DM-worker will pull the binlogs starting from the latest GTID. |
+| `enable-relay` | Determines whether to enable the relay log feature. The default value is `false`. Since DM v2.0.2, this configuration item is deprecated. To [enable the relay log feature](/dm/relay-log.md#enable-and-disable-relay-log), use the `start-relay` command instead. |
+| `relay-binlog-name` | Specifies the file name from which DM-worker starts to pull the binlog. For example, `"mysql-bin.000002"`. It only works when `enable_gtid` is `false`. If this parameter is not specified, DM-worker will start pulling from the earliest binlog file being replicated. Manual configuration is generally not required. |
+| `relay-binlog-gtid` | Specifies the GTID from which DM-worker starts to pull the binlog. For example, `"e9a1fc22-ec08-11e9-b2ac-0242ac110003:1-7849"`. It only works when `enable_gtid` is `true`. If this parameter is not specified, DM-worker will start pulling from the latest GTID being replicated. Manual configuration is generally not required. |
 | `relay-dir` | Specifies the relay log directory. |
 | `host` | Specifies the host of the upstream database. |
 | `port` | Specifies the port of the upstream database. |

dm/maintain-dm-using-tiup.md

@@ -185,7 +185,7 @@ For example, to scale out a DM-worker node in the `prod-cluster` cluster, take t
 >
 > For clusters earlier than v2.0.5, you can use dmctl v2.0.5 or later to export and import the data source and task configuration files.
 >
-> For clusters later than v2.0.2, currently, it is not supported to automatically import the configuration related to relay worker. You can use `start-relay` command to manually [start relay log](/dm/relay-log.md#start-and-stop-the-relay-log-feature).
+> For clusters later than v2.0.2, currently, it is not supported to automatically import the configuration related to relay worker. You can use `start-relay` command to manually [start relay log](/dm/relay-log.md#enable-and-disable-relay-log).
 
 The rolling upgrade process is made as transparent as possible to the application, and does not affect the business. The operations vary with different nodes.