Change tex -> bibtex for nicer syntax highlighting.

PiperOrigin-RevId: 387546070
Change-Id: I24cce3825801dde09be70970cf48141679762a2a

README.md

@@ -329,7 +329,7 @@ structures that were available at the start of CASP14.
 
 If you use the code or data in this package, please cite:
 
-```tex
+```bibtex
 @Article{AlphaFold2021,
   author  = {Jumper, John and Evans, Richard and Pritzel, Alexander and Green, Tim and Figurnov, Michael and Ronneberger, Olaf and Tunyasuvunakool, Kathryn and Bates, Russ and {\v{Z}}{\'\i}dek, Augustin and Potapenko, Anna and Bridgland, Alex and Meyer, Clemens and Kohl, Simon A A and Ballard, Andrew J and Cowie, Andrew and Romera-Paredes, Bernardino and Nikolov, Stanislav and Jain, Rishub and Adler, Jonas and Back, Trevor and Petersen, Stig and Reiman, David and Clancy, Ellen and Zielinski, Michal and Steinegger, Martin and Pacholska, Michalina and Berghammer, Tamas and Bodenstein, Sebastian and Silver, David and Vinyals, Oriol and Senior, Andrew W and Kavukcuoglu, Koray and Kohli, Pushmeet and Hassabis, Demis},
   journal = {Nature},