docs: Add use citations from ICHEP 2022 proceedings (#2066)

* Add use citation from 'The IRIS-HEP Analysis Grand Challenge' and
 'pyhf: a pure-Python statistical fitting library with tensors and
  automatic differentiation' which both appear in the ICHEP 2022
  proceedings.
   - https://inspirehep.net/literature/2598292
   - https://inspirehep.net/literature/2598491

Author: matthewfeickert

docs/bib/use_citations.bib

@@ -1,3 +1,27 @@
+% 2022-11-26
+@article{Feickert:2022lzh,
+    author = "Feickert, Matthew and Heinrich, Lukas and Stark, Giordon",
+    title = "{pyhf: a pure-Python statistical fitting library with tensors and automatic differentiation}",
+    doi = "10.22323/1.414.0245",
+    journal = "PoS",
+    volume = "ICHEP2022",
+    pages = "245",
+    month = "11",
+    year = "2022"
+}
+
+% 2022-11-26
+@article{Held:2022sfw,
+    author = "Held, Alexander and Shadura, Oksana",
+    title = "{The IRIS-HEP Analysis Grand Challenge}",
+    doi = "10.22323/1.414.0235",
+    journal = "PoS",
+    volume = "ICHEP2022",
+    pages = "235",
+    month = "11",
+    year = "2022"
+}
+
 % 2022-10-06
 @phdthesis{Biswas:2022vtp,
     author = "Biswas, Diptaparna",