docs: add arxiv citation

citation.cff

@@ -0,0 +1,28 @@
+cff-version: 1.2.0
+message: "If you use this software, please cite it as below."
+authors:
+  - family-names: "Hansen"
+    given-names: "Lasse"
+    orcid: "https://orcid.org/0000-0003-1113-4779"
+  - family-names: "Enevoldsen"
+    given-names: "Kenneth"
+    orcid: "https://orcid.org/0000-0001-8733-0966"
+
+title: "TextDescriptives: A Python package for calculating a large variety of statistics from text"
+version: 2.0.10
+date-released: 2020-01-28
+url: "https://github.com/HLasse/TextDescriptives"
+
+preferred-citation:
+  type: article
+  authors:
+    - family-names: "Hansen"
+      given-names: "Lasse"
+      orcid: "https://orcid.org/0000-0003-1113-4779"
+    - family-names: "Enevoldsen"
+      given-names: "Kenneth"
+      orcid: "https://orcid.org/0000-0001-8733-0966"
+  doi: "https://doi.org/10.48550/arxiv.2301.02057"
+  journal: "arXiv"
+  title: "TextDescriptives: A Python package for calculating a large variety of statistics from text"
+  year: 2023