DOC: added zenodo doi badge and CITATION.cff

CITATION.cff

@@ -0,0 +1,12 @@
+cff-version: 1.2.0
+message: "If you use this software, please cite it as below."
+authors:
+- family-names: Hörmann
+  given-names: Johannes Laurin
+  orcid: 0000-0001-5867-695X
+title: dserver-direct-mongo-plugin
+version: 0.4.1
+identifiers:
+  - type: doi
+    value: 10.5281/zenodo.12701908
+date-released: 2024-07-09

README.rst

@@ -10,8 +10,10 @@ dserver Direct Mongo Plugin
     :target: https://github.com/livMatS/dserver-direct-mongo-plugin/tags
 .. |test| image:: https://img.shields.io/github/actions/workflow/status/livMatS/dserver-direct-mongo-plugin/test.yml?branch=main&label=tests
     :target: https://github.com/livMatS/dserver-direct-mongo-plugin/actions/workflows/test.yml
+.. |zenodo| image:: https://zenodo.org/badge/DOI/10.5281/zenodo.12701908.svg
+    :target: https://doi.org/10.5281/zenodo.12701908
 
-|dtool| |pypi| |tag| |test|
+|dtool| |pypi| |tag| |test| |zenodo|
 
 - GitHub: https://github.com/livMatS/dserver-direct-mongo-plugin
 - PyPI: https://pypi.org/project/dserver-direct-mongo-plugin/