[IMPROVEMENT] More understandable documentation for the serializationLibrary option

Created by: obfischer

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
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Description

The documentation of the generator for Java should be a little bit more presise on the relation between the options serializationLibrary and library. It took me some time to realise, that library has precedence over serializationLibrary.

openapi-generator version

5.2.1

OpenAPI declaration file content or url

Not applicable.

Generation Details

This issue is about documentation, not generation.

Steps to reproduce

N/A

Related issues/PRs

No known ones.

Suggest a fix

I will provide a pull request for this issue.