docs: add DataJoint 2.0 citation to what's new pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dimitri-yatsenko

src/explanation/whats-new-2.md

@@ -6,6 +6,8 @@ DataJoint 2.0 is a major release that establishes DataJoint as a mature framewor
 >
 > This page summarizes new features and concepts. For step-by-step migration instructions, see the **[Migration Guide](../how-to/migrate-to-v20.md/)**.
 
+> **Citation:** Yatsenko D, Nguyen TT. *DataJoint 2.0: A Computational Substrate for Agentic Scientific Workflows.* arXiv:2602.16585. 2026. [doi:10.48550/arXiv.2602.16585](https://doi.org/10.48550/arXiv.2602.16585)
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 ## Overview
 
 DataJoint 2.0 introduces fundamental improvements to type handling, job coordination, and object storage while maintaining compatibility with your existing pipelines during migration. Key themes:

src/explanation/whats-new-22.md

@@ -4,6 +4,8 @@ DataJoint 2.2 introduces **isolated instances** and **thread-safe mode** for app
 
 > **Upgrading from 2.0 or 2.1?** No breaking changes. All existing code using `dj.config` and `dj.Schema()` continues to work. The new Instance API is purely additive.
 
+> **Citation:** Yatsenko D, Nguyen TT. *DataJoint 2.0: A Computational Substrate for Agentic Scientific Workflows.* arXiv:2602.16585. 2026. [doi:10.48550/arXiv.2602.16585](https://doi.org/10.48550/arXiv.2602.16585)
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 ## Overview
 
 DataJoint has traditionally used a global singleton pattern: one configuration (`dj.config`), one connection (`dj.conn()`), shared across all tables in a process. This works well for interactive sessions and single-user scripts, but breaks down when: