Adds CITATION.cff file to make this repository citeable

CITATION.cff

@@ -0,0 +1,30 @@
+cff-version: 1.2.0
+title: 'jsonldschema'
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+authors:
+  - affiliation: UK Atomic Energy Authority
+    given-names: Alejandra
+    family-names: Gonzalez-Beltran
+    orcid: 'https://orcid.org/0000-0003-3499-8262'
+  - given-names: Susanna-Assunta
+    family-names: Sansone
+    orcid: 'https://orcid.org/0000-0001-5306-5690'
+    email: susanna-assunta.sansone@oerc.ox.ac.uk
+    affiliation: University of Oxford
+  - given-names: Dominique
+    family-names: Batista
+    orcid: 'https://orcid.org/0000-0002-2109-489X'
+    affiliation: T-Cypher Bio
+    email: dominique.batista@oerc.ox.ac.uk
+repository-code: 'https://github.com/FAIRsharing/jsonldschema'
+url: 'https://jsonldschema.readthedocs.io'
+abstract: >-
+  The JSONLDschema python package offers functionality to
+  support the creation and use of machine-actionable and
+  FAIR (Findable, Accessible, Interoperable and Reusable)
+  metadata models expressed as JSON-schemas for JSON-LD
+  data.
+license: BSD-3-Clause