F citation cff

Adding a citation.cff file, see: https://citation-file-format.github.io/

CITATION.cff

+cff-version: 1.2.0
+message: "If you use this software, please cite it as below."
+authors:
+  - family-names:
+    given-names:
+    orcid: https://orcid.org/0000-0002-4022-432X
+title: CaosDB - Server
+version: 0.8.1
+doi: 10.3390/data4020083
+date-released: 2022-11-07
\ No newline at end of file