[BP-1.19][FLINK-34265][doc] Add the doc of named parameters (#24260)

[hackergin]

What is the purpose of the change

Add doc of named parameters

Brief change log

• Add doc of named parameters

Verifying this change

Add doc , no need to test.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)

[flinkbot]

CI report:

• dbfc316 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[hackergin]

@flinkbot run azure

[hackergin]

@fsk119 Please help take a look at this when you have time.