Update the limitation of the Global index (pingcap#19841)

partitioned-table.md

@@ -1796,7 +1796,7 @@ ALTER TABLE t1 PARTITION BY HASH (col1) PARTITIONS 3 UPDATE INDEXES (uidx12 LOCA
     ALTER TABLE ... ADD UNIQUE INDEX(col3, col1) GLOBAL;
     ```
 
-- DDL operations such as `DROP PARTITION`, `TRUNCATE PARTITION`, `REORGANIZE PARTITION`, and `EXCHANGE PARTITION` also trigger updates to global indexes. These DDL operations need to wait for the global index updates to complete before returning results, which increases the execution time accordingly. This is particularly evident in data archiving scenarios, such as `DROP PARTITION` and `TRUNCATE PARTITION`. Without global indexes, these operations can typically complete immediately. However, with global indexes, the execution time increases as the number of indexes that need to be updated grows.
+- DDL operations such as `DROP PARTITION`, `TRUNCATE PARTITION`, and `REORGANIZE PARTITION` also trigger updates to global indexes. These DDL operations need to wait for the global index updates to complete before returning results, which increases the execution time accordingly. This is particularly evident in data archiving scenarios, such as `DROP PARTITION` and `TRUNCATE PARTITION`. Without global indexes, these operations can typically complete immediately. However, with global indexes, the execution time increases as the number of indexes that need to be updated grows.
 - Tables with global indexes do not support the `EXCHANGE PARTITION` operation.
 - By default, the primary key of a partitioned table is a clustered index and must include the partition key. If you require the primary key to exclude the partition key, you can explicitly specify the primary key as a non-clustered global index when creating the table, for example, `PRIMARY KEY(col1, col2) NONCLUSTERED GLOBAL`.
 - If a global index is added to an expression column, or a global index is also a prefix index (for example `UNIQUE KEY idx_id_prefix (id(10)) GLOBAL`), you need to collect statistics manually for this global index.