Update docs of Array.exists2 to mention ArgumentException being thrown

[gimbling-away]

Description

The example of Array.exists2 originally says that it evaluates to false, however it throws ArgumentException instead

Either the example itself could be fixed, or what it evaluates to could be fixed

I've changed the message, but if the example is supposed to be fixed instead, I'll do that instead

Fixes # (issue, if applicable)

Checklist

• Test cases added

• Performance benchmarks added in case of performance changes

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[github-actions]

❗ Release notes required

@gimbling-away,

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Change path	Release notes path	Description
src/FSharp.Core	docs/release-notes/.FSharp.Core/9.0.100.md	No release notes found or release notes format is not correct

[vzarytovskii]

Second example will throw as well. I think we should instead make one example which returns true, one which returns false and one which throws.