feat(utility): add java-refined

* Add java-refined to Utility section

java-refined provides refinement types for Java 8+ — types constrained
by predicates (e.g. PositiveInt, NonBlankString, EmailString). It ships
204 ready-to-use refined types with zero runtime dependencies, 100% test
coverage, and 95%+ mutation testing scores.

GitHub: https://github.com/JunggiKim/java-refined
Maven Central: io.github.junggikim:java-refined

* fix: merge two sentences into one

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Co-authored-by: Andreas Kull <akullpp@gmail.com>