docs: Add use citation from collider signatures of coannihilating dar…

…k matter paper (#1604)

* Add use citation from 'Collider Signatures of Coannihilating Dark Matter in Light of the B-Physics Anomalies'
   - c.f. https://inspirehep.net/literature/1924354

docs/bib/use_citations.bib

@@ -1,3 +1,15 @@
+% 2021-09-17
+@article{Baker:2021llj,
+    author = "Baker, Michael J. and Faroughy, Darius A. and Trifinopoulos, Sokratis",
+    title = "{Collider Signatures of Coannihilating Dark Matter in Light of the B-Physics Anomalies}",
+    eprint = "2109.08689",
+    archivePrefix = "arXiv",
+    primaryClass = "hep-ph",
+    month = "9",
+    year = "2021",
+    journal = ""
+}
+
 % 2021-09-10
 @article{Cranmer:2021urp,
     author = "Cranmer, Kyle and others",