cloud: Premium supports data migration (#22821)

Author: alastori

TOC-tidb-cloud-premium.md

@@ -111,6 +111,8 @@
 - Migrate or Import Data
   - [Overview](/tidb-cloud/tidb-cloud-migration-overview.md)
   - Migrate Data into TiDB Cloud
+    - [Migrate Existing and Incremental Data Using Data Migration](/tidb-cloud/migrate-from-mysql-using-data-migration.md)
+    - [Migrate Incremental Data Using Data Migration](/tidb-cloud/migrate-incremental-data-from-mysql-using-data-migration.md)
     - [Migrate from TiDB Self-Managed to TiDB Cloud Premium](/tidb-cloud/premium/migrate-from-op-tidb-premium.md)
     - [Migrate and Merge MySQL Shards of Large Datasets](/tidb-cloud/migrate-sql-shards.md)
     - [Migrate from Amazon RDS for Oracle Using AWS DMS](/tidb-cloud/migrate-from-oracle-using-aws-dms.md)