Create CITATION.cff (OHIF#2503)

CITATION.cff

@@ -0,0 +1,35 @@
+cff-version: 1.2.0
+message: "If you use this software, please cite it as below."
+authors:
+  - family-names: "Ziegler"
+    given-names: "Erik"
+    orcid: "http://orcid.org/0000-0003-1857-8129"
+  - family-names: "Urban"
+    given-names: "Trinity"
+  - family-names: "Brown"
+    given-names: "Danny"
+  - family-names: "Petts"
+    given-names: "James"
+  - family-names: "Pieper"
+    given-names: "Steve D"
+  - family-names: "Lewis"
+    given-names: "Rob"
+  - family-names: "Hafey"
+    given-names: "Chris"
+  - family-names: "Harris"
+    given-names: "Gordon J"
+doi: 10.1200/CCI.19.00131
+date-released: 2020-04-23
+url: "https://github.com/OHIF/Viewers"
+identifiers:
+  - type: doi
+    value: 10.1200/CCI.19.00131
+  - type: other
+    value: urn:issn:2473-4276
+  - type: other
+    value: pmcid:7259879
+  - type: other
+    value: pmid:32324447
+title: >-
+  Open Health Imaging Foundation Viewer: An Extensible Open-Source Framework for
+  Building Web-Based Imaging Applications to Support Cancer Research