DOC: Update mazeika2023tdc citation to MLR proceedings page (microsoft#2104)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: romanlutz

doc/references.bib

@@ -68,8 +68,8 @@ @misc{mazeika2023tdc
   title     = {The Trojan Detection Challenge 2023 ({LLM} Edition)},
   author    = {Mantas Mazeika and Andy Zou and Norman Mu and Long Phan and Zifan Wang and Chunru Yu and Adam Khoja and Fengqing Jiang and Aidan O'Gara and Ellie Sakhaee and Zhen Xiang and Arezoo Rajabi and Dan Hendrycks and Radha Poovendran and Bo Li and David Forsyth},
   year      = {2023},
-  url       = {https://trojandetection.ai/},
-  note      = {NeurIPS 2023 Trojan Detection Challenge competition. No canonical paper write-up; the cited URL is the official competition website.},
+  url       = {https://proceedings.mlr.press/v220/mazeika23a.html},
+  note      = {NeurIPS Trojan Detection Challenge series. Official challenge site may be unavailable; using the proceedings page for archival access.},
 }
 
 @misc{promptfoo2025ccp,