Align 3 PRs from docs-cn (pingcap#7000)

* Align 3 PR from docs-cn

* Update sql-plan-replayer.md

Co-authored-by: Liuxiaozhen12 <82579298+Liuxiaozhen12@users.noreply.github.com>

Co-authored-by: Liuxiaozhen12 <82579298+Liuxiaozhen12@users.noreply.github.com>

configure-memory-usage.md

@@ -100,7 +100,7 @@ The following example constructs a memory-intensive SQL statement that triggers
 
 2. Execute `CREATE TABLE t(a int);` and insert 1000 rows of data.
 
-3. Execute `select * from t t1 join t t1 join t t3 order by t1.a`. This SQL statement outputs one billion records, which consumes a large amount of memory and therefore triggers the alarm.
+3. Execute `select * from t t1 join t t2 join t t3 order by t1.a`. This SQL statement outputs one billion records, which consumes a large amount of memory and therefore triggers the alarm.
 
 4. Check the `tidb.log` file which records the total system memory, current system memory usage, memory usage of the tidb-server instance, and the directory of status files.
 

sql-plan-replayer.md

@@ -49,7 +49,11 @@ analyze table t;
 plan replayer dump explain select * from t;
 ```
 
-`PLAN REPLAYER DUMP` packages the table information above into a `ZIP` file and returns the file identifier as the execution result.
+`PLAN REPLAYER DUMP` packages the table information above into a `ZIP` file and returns the file identifier as the execution result. This file is a one-time file. After the file is downloaded, TiDB will delete it.
+
+> **Note:**
+>
+> The `ZIP` file is stored in a TiDB cluster for at most one hour. After one hour, TiDB will delete it.
 
 ```sql
 MySQL [test]> plan replayer dump explain select * from t;

tidb-configuration-file.md

@@ -255,7 +255,8 @@ Configuration items related to log files.
 #### `max-size`
 
 - The size limit of the log file.
-- Default value: 300MB
+- Default value: 300
+- Unit: MB
 - The maximum size is 4GB.
 
 #### `max-days`