Change required: Adds support for SET BATCH_PARALLELISM

[CharlieSYH]

Related code PR

risingwavelabs/risingwave#8552

issue: risingwavelabs/risingwave#7558

Which part(s) of the docs might be affected or should be updated? And how?

Release notes

Adds support for SET BATCH_PARALLELISM. You can use this session variable to configure parallelism for batch queries.

This is from v0.18.0.

@hengm3467 Other than mentioning it in the release notes, do we need to document them (like SET STREAMING_PARALLELISM, set batch_parallelism, SET VISIBILITY_MODE) on a reference page?

Reference

Adding the support for SET BATCH_PARALLELISM in the batch query jobs in RisingWave.

[hengm3467]

@neverchanje Do we need to document how to configure these meta settings?

[hengm3467]

Now we have all the runtime parameters documented on this page: https://www.risingwave.dev/docs/current/view-configure-runtime-parameters/

Close as completed.