Adding a citation file.

Author: danfunk

CITATION.cff

@@ -0,0 +1,26 @@
+cff-version: 1.2.0
+message: "If you use SpiffWorkflow in your work, please cite it as follows."
+title: "SpiffWorkflow"
+version: "3.1.1"
+doi: "10.5281/zenodo.14966563"
+date-released: "2025-03-04"
+url: "https://github.com/sartography/SpiffWorkflow"
+repository-code: "https://github.com/sartography/SpiffWorkflow"
+license: "LGPL-3.0"
+authors:
+  - family-names: "Esswein"
+    given-names: "Elizabeth"
+    affiliation: "Sartography"
+  - family-names: "Abels"
+    given-names: "Samuel"
+    affiliation: "Independent Developer"
+  - family-names: "Funk"
+    given-names: "Daniel"
+    orcid: "0000-0003-0723-2253"
+    affiliation: "Independent Developer"
+  - family-names: "Jon"
+    given-names: "Herron"
+    affiliation: "Sartography"
+  - family-names: "McDonald"
+    given-names: "Kelly"
+    affiliation: "Sartography"