Added CITATION.cff

CITATION.cff

+cff-version: 1.2.0
+title: 'FACT Data: Buildings Footprint and Height'
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+doi: 10.17605/OSF.IO/CHDJR
+authors:
+  - given-names: Riccardo
+    family-names: Boero
+    email: ribo@nilu.no
+    orcid: 'https://orcid.org/0000-0002-7468-9096'
+    affiliation: NILU
+identifiers:
+  - type: doi
+    value: 10.17605/OSF.IO/CHDJR
+    description: This DOI represents all software versions.
+repository-code: 'https://git.nilu.no/fact/data/FACT_bldgs'
+url: 'https://osf.io/chdjr/'
+abstract: >-
+  Database of ML detected building footprints and height (only US and Europe included here).
+keywords:
+  - Machine Learning
+  - Buildings footprint
+  - Buildings height
+license: GPL-3.0-only
+