docs: Document the noReturn option on write operations

[marcelomendoncasoares]

Summary

The batch and filtered write methods accept noReturn: true, which runs the write without reading the affected rows back. The CRUD page had no mention of it.

Changes

• Add a "Skipping returned rows" section to the CRUD page.
• Show noReturn: true on updateWhere and explain that the write still runs with the same filters, conflict handling, transaction, and atomicity guarantees.
• Describe the performance tradeoff and when it is worth taking.
• List the methods that accept it: insert, update, updateWhere, upsert, delete, and deleteWhere. The single-row variants always return their row.
• Note that orderBy and orderByList no longer affect the (empty) result, but still decide which rows limit and offset select.

Note on merge order

The method list includes upsert, which is documented in the companion PR for the upsert methods. If this PR merges first, upsert is named here before it has a section of its own on the page.

Reference

• feat: Add a noReturn to all ORM methods that return a list serverpod#5371
• A database updateWhere method that does not return all the updated rows serverpod#5118