Add citation info and link to JOSS paper

CITATION.cff

@@ -0,0 +1,52 @@
+cff-version: "1.2.0"
+authors:
+- family-names: Bartels
+  given-names: Tinko Sebastian
+  orcid: "https://orcid.org/0000-0002-0084-7100"
+- family-names: Fisikopoulos
+  given-names: Vissarion
+  orcid: "https://orcid.org/0000-0002-0780-666X"
+- family-names: Gehrels
+  given-names: Barend
+- family-names: Karavelas
+  given-names: Menelaos
+- family-names: Lalande
+  given-names: Bruno
+- family-names: Łoskot
+  given-names: Mateusz
+- family-names: Wulkiewicz
+  given-names: Adam
+doi: 10.5281/zenodo.20281747
+message: If you use this software, please cite our article in the
+  Journal of Open Source Software.
+preferred-citation:
+  authors:
+  - family-names: Bartels
+    given-names: Tinko Sebastian
+    orcid: "https://orcid.org/0000-0002-0084-7100"
+  - family-names: Fisikopoulos
+    given-names: Vissarion
+    orcid: "https://orcid.org/0000-0002-0780-666X"
+  - family-names: Gehrels
+    given-names: Barend
+  - family-names: Karavelas
+    given-names: Menelaos
+  - family-names: Lalande
+    given-names: Bruno
+  - family-names: Łoskot
+    given-names: Mateusz
+  - family-names: Wulkiewicz
+    given-names: Adam
+  date-published: 2026-05-19
+  doi: 10.21105/joss.10328
+  issn: 2475-9066
+  issue: 121
+  journal: Journal of Open Source Software
+  publisher:
+    name: Open Journals
+  start: 10328
+  title: "Boost.Geometry: A Generic C++ Geometry Library"
+  type: article
+  url: "https://joss.theoj.org/papers/10.21105/joss.10328"
+  volume: 11
+title: "Boost.Geometry: A Generic C++ Geometry Library"

README.md

@@ -7,6 +7,7 @@ Boost.Geometry, part of collection of the [Boost C++ Libraries](http://github.co
 [![Wiki](https://img.shields.io/badge/-wiki-4480cc.png)](https://github.com/boostorg/geometry/wiki)
 [![Mailing List](https://img.shields.io/badge/-mailing%20list-4eb899.png)](http://lists.boost.org/geometry/)
 [![Chat](https://badges.gitter.im/boostorg/geometry.png)](https://gitter.im/boostorg/geometry?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![DOI](https://img.shields.io/badge/DOI-10.21105%2Fjoss.10328-4480cc.png)](https://doi.org/10.21105/joss.10328)
 
 ### Test results