[hotfix] [docs]Fix miss semicolon on SELECT & WHERE clause example sql

[camilesing]

What is the purpose of the change

(For example: This pull request makes task deployment go through the blob server, rather than through RPC. That way we avoid re-transferring them on each deployment (during recovery).)
Fix miss semicolon on SELECT & WHERE clause example sql.

Brief change log

Add semicolon for miss semicolon example sql.

Verifying this change

Since the changes affect the doc examples and there are no tests. I copied the snippets and verified (compiled) them locally.

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 / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• 4740ab5 Azure: SUCCESS

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[snuyanzin]

Thanks for the contribution

IIRC semicolon is just a statement terminator and it always should be used to inform parser that the statement is finished, so it is ok to not specify it in such doc having this in mind.
Even more there is no concrete example with concrete environment.
For instance if we try to use these examples with Flink SQL Client then yes we need to use semicolon, however if we try to use this with Table SQL then there is no need for that