[FLINK-37087][doc] Add docs for alter materialized table as query

[hackergin]

What is the purpose of the change

Add docs for alter materialized table as query

Brief change log

• Add docs for alter materialized table as query

Verifying this change

This change only contains document change.

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)
• If yes, how is the feature documented? (not applicable)

[davidradl]

I see that the REFRESH keyword is mentioned - there is a some explanation of this in the file but not how the partition piece works and when you would want to use it.
I see we have added SUSPEND and RESUME, it would be useful to describe or link to how these work - including how the supplied list of keys should be used.

[flinkbot]

CI report:

• 8d36e44 UNKNOWN
• acc279c Azure: SUCCESS

Bot commands

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[davidradl]

Reviewed by Chi on 23/01/2025 Go back to the submitter with review comments.

[lsyldliu]

@hackergin Thanks for your contribution, I left some comments.

[hackergin]

I see that the REFRESH keyword is mentioned - there is a some explanation of this in the file but not how the partition piece works and when you would want to use it. I see we have added SUSPEND and RESUME, it would be useful to describe or link to how these work - including how the supplied list of keys should be used.

@davidradl This document is solely intended to explain how users can use it. If we need to introduce the underlying implementation to users, I think we should have a separate document to explain the overall process.