add cff for ifcblender

src/ifcblender/CITATION.cff

@@ -0,0 +1,18 @@
+# This CITATION.cff file was generated with cffinit.
+# Visit https://bit.ly/cffinit to generate yours today!
+
+cff-version: 1.2.0
+title: ifcblender
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+authors:
+  - name: IfcOpenShell contributors
+repository-code: >-
+  https://github.com/IfcOpenShell/IfcOpenShell/tree/v0.7.0/src/ifcblender
+abstract: Historic Blender IFC import add-on
+keywords:
+  - Blender
+  - IFC
+license: LGPL-3.0-or-later