update documentation about multiValueHandling

[knorth55]

Update documentation about multiValueHandling

Description

I'm a druid beginner, so I'm not super sure, but multiValueHandling param has only effects on string type dimension.
I read source codes and PRs below, and it seems the multiValueHandling sorts only string value.
So I update the doc to add the information about it.
#2541
#10695

I tried to create supervisor with long data with multiValueHandling as ARRAY, but druid always override multiValueHandling as SORTED_ARRAY.
I though it is weird and I read the doc, but doc seems that we can set the value for all types.
I spent long time for this survey, so I want to clarify it in the documents.

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Key changed/added classes in this PR

• docs

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[vtlim]

@knorth55 Thanks for your first contribution! Left a suggestion for docs styling.

[gianm]

thanks 🎉 !