[Improve][Docs] Optimize Doris, Paimon, Redis, and StarRocks connector docs

[DanielCarter-stack]

Summary

This PR optimizes the user-facing documentation for five Apache SeaTunnel connectors (Doris, Paimon, Redis, StarRocks, both source and sink pages, English and Chinese) so the docs more accurately reflect the connector behavior and surface commonly used e2e patterns as first-class examples.

What changed

• Doris (source): Fixed the asynchronous Arrow queue option name (doris.request.retriesdoris.deserialize.queue.size → doris.deserialize.queue.size) and added a multi-source example that reads from two Doris databases with per-table doris.read.field and doris.filter.query settings, then writes back to Doris with ${table_name}.
• Doris (sink): Added a data_save_mode = CUSTOM_PROCESSING example that uses custom_sql to seed the target table before the synchronization task, in both English and Chinese pages.
• Paimon (source): Added complete scan.tag-name and incremental-between query examples that show how to read a single tag snapshot and how to read the rows added between two tags.
• Paimon (sink): Added a streaming CDC → non-primary-key Paimon table example that combines paimon.table.non-primary-key = true with paimon.table.write-props, in both English and Chinese pages.
• Redis (source): Added a single-node db_num example that reads from one database and writes to another in the same pipeline, plus an FAQ section with a read_key_enabled configuration example and a cluster-mode multi-table reading example.
• Redis (sink): Added a multi-table sink example that uses ${table_name} in the key template, and a FAQ section explaining value_field, expire, and the limitation that each sink instance can only target a single Redis database.
• StarRocks (sink): Added an automatic table creation example with table_options (storage_format, etc.) and a Zeta timer-flush example that combines MySQL-CDC, checkpoint.interval, and sink.flush.interval, in both English and Chinese pages.

Validation

• All modified files are under docs/en/connectors/{source,sink} and docs/zh/connectors/{source,sink}; no source code, config files, or public API contracts were changed.
• All additions reuse e2e patterns that already exist in seatunnel-e2e/seatunnel-connector-v2-e2e/connector-{doris,paimon,redis,starrocks}-e2e.
• Chinese pages are updated in lockstep with English pages and keep the Chinese-language convention for connector feature lists.

Checklist

• Docs only
• Follows the existing [Type][Module] commit message style
• No new dependencies, no removed config options, no public API changes
• Draft PR — ready to be promoted once CI is green