[docs] Upgrade flink docker image version to latest Flink 2.2 for quickstarts

[wuchong]

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Description

Currently, the quickstart demos use Flink 1.20 as the base image version. However, many new features—such as Delta Join—are only available in newer versions like Flink 2.2. Upgrading the base image to Flink 2.2 would allow users to reuse the existing Docker Compose environment to easily try out these advanced features.

Willingness to contribute

• I'm willing to submit a PR!

[wuchong]

Hi @leekeiabstraction since you are familiar about the the quickstart documentation. Do you want to take this task?

[leekeiabstraction]

Would be very happy to contribute, however what is the priority or timeline we are aiming for this? My availability is slightly limited in the coming week.