Add citation of ArXiv paper

[edoaltamura]

Summary

Adds the citation of the Qiskit ML overview paper on ArXiv (https://arxiv.org/abs/2505.17756).

[coveralls]

Pull Request Test Coverage Report for Build 15275315230

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 90.821%

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Totals
Change from base Build 15191116434:	0.0%
Covered Lines:	4492
Relevant Lines:	4946

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💛 - Coveralls