[Improvement]: Update the doc for optimizer management

[klion26]

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• [x] I have searched in the issues and found no similar issues.

What would you like to be improved?

In 0.8 we have improved the user-interface for optimizer create/scale-out, but the doc did not respect the latest version, we need to change this.

in the version before 0.8 there is a scale-out in optimizer-group, but not in 0.8, and user need to create optimizer in optimizers tab

How should we improve?

No response

Are you willing to submit PR?

• [ ] Yes I am willing to submit a PR!

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[klion26]

we need to improve this page https://amoro.apache.org/docs/0.8.0/managing-optimizers/

[zhoujinsong]

Fixed this issue in the quickstart by https://github.com/apache/amoro-site/pull/57

[klion26]

implemented by #3641