Update documents for cross-partition scan and import feature #2616

Job	Run time
Gradle check	3m 39s
Cassandra 3.11 integration test	8m 0s
Cassandra 3.0 integration test	7m 25s
Lint dockerfiles	21s
Cosmos DB integration test	18m 5s
DynamoDB integration test	12m 17s
MariaDB 10 integration test	3m 28s
MySQL 5.7 integration test	4m 2s
MySQL 8.0 integration test	6m 29s
MySQL 8.1 integration test	5m 51s
Oracle 18 integration test	8m 22s
Oracle 21 integration test	10m 16s
Oracle 23 integration test	11m 3s
PostgreSQL 13 integration test	2m 20s
PostgreSQL 12 integration test	2m 16s
PostgreSQL 14 integration test	2m 51s
PostgreSQL 15 integration test	2m 18s
SQLite 3 integration test	4m 52s
SQL Server 2017 integration test	4m 37s
SQL Server 2019 integration test	4m 35s
SQL Server 2022 integration test	5m 1s
Multi-storage integration test	3m 19s
ScalarDB Server integration test	5m 51s
	2h 17m 18s

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