[hotfix][doc] mvn 3.8.6 is recommended or higher version could be used

[JingGe]

What is the purpose of the change

update the doc to help developer use the feasible maven version.

Brief change log

• pointed out that 3.8.6 is recommended according to https://lists.apache.org/thread/jbw3lzzoq5w16ckco3fc9xokycs3f22x.
• Higher version could also be used. I personally tested with 3.9.1

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

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

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CI report:

• 2863484 Azure: SUCCESS

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