docs: add citation block (BibTeX + plain text)

README.md

@@ -72,6 +72,32 @@ With `explore=False` the policy is deterministic — same scenario seed and inte
 - Episodes per scenario: 10,000
 - See [training scripts](https://github.com/aiacontext/marginplay/tree/main/scripts) for full configuration
 
+## Citation
+
+If you use these weights or the Margin Play simulator in academic work, please cite:
+
+```bibtex
+@unpublished{leitaofilho2026marginplay,
+  title  = {Margin Play: A Multi-Agent System for Public Policy Analysis
+            in the Brazilian Equatorial Margin},
+  author = {Leit{\~a}o Filho, Antonio de Sousa and
+            Lima, Fabr{\'\i}cio Saul and
+            Santos, Selby Mykael Lima dos and
+            Sousa, Rejani Bandeira Vieira and
+            Jesus, Lu{\'\i}s Jorge Mesquita de and
+            Silva, Dennys Correia da and
+            Barros Filho, Allan Kardec Duailibe},
+  year   = {2026},
+  note   = {Manuscript in preparation},
+}
+```
+
+Plain text:
+
+> Leitão Filho, A. S., Lima, F. S., Santos, S. M. L. dos, Sousa, R. B. V., Jesus, L. J. M. de, Silva, D. C. da, & Barros Filho, A. K. D. (2026). *Margin Play: A Multi-Agent System for Public Policy Analysis in the Brazilian Equatorial Margin*. Manuscript in preparation.
+
+**Corresponding author:** Antonio de Sousa Leitão Filho — [antonio@aiacontext.com](mailto:antonio@aiacontext.com) — ORCID [0009-0002-1705-3611](https://orcid.org/0009-0002-1705-3611).
+
 ## License
 
 MIT.