fix: remove unnessary part

Author: 0xPoe

statistics.md

@@ -497,10 +497,6 @@ After enabling the synchronously loading statistics feature, you can control how
 
 </CustomContent>
 
-### Refresh in-memory statistics
-
-After you import or restore statistics directly into the TiDB system tables, run [`REFRESH STATS`](/sql-statements/sql-statement-refresh-stats.md) to reload the persisted statistics into the TiDB servers' memory. You can target individual tables, all tables in a database, or the entire cluster (`*.*`), and choose between lightweight (`LITE`) and full (`FULL`) initialization. Add the optional `CLUSTER` keyword when you need every TiDB node to refresh its in-memory statistics.
-
 ## Export and import statistics
 
 This section describes how to export and import statistics.