Add CITATION.cff and BibTeX to the readme

Author: stephane-caron

CITATION.cff

@@ -0,0 +1,23 @@
+cff-version: 1.2.0
+message: "If you find this code helpful, please cite it as below."
+title: "robot_descriptions.py: Robot descriptions in Python"
+version: 1.8.1
+date-released: 2024-01-29
+url: "https://github.com/robot-descriptions/robot_descriptions.py"
+license: "Apache-2.0"
+authors:
+- family-names: "Caron"
+  given-names: "Stéphane"
+  orcid: "https://orcid.org/0000-0003-2906-692X"
+- family-names: "Romualdi"
+  given-names: "Giulio"
+  orcid: "https://orcid.org/0000-0002-6461-3231"
+- family-names: "Kozlov"
+  given-names: "Lev"
+- family-names: "Ordonez"
+  given-names: "Daniel"
+- family-names: "Tadashi Kussaba"
+  given-names: "Hugo"
+  orcid: "https://orcid.org/0000-0002-7336-1443"
+- family-names: "Bang"
+  given-names: "Seung Hyeon"

README.md

@@ -253,6 +253,22 @@ New robot descriptions are welcome! Check out the [guidelines](https://github.co
 
 Thanks to the maintainers of all the git repositories that made these robot descriptions available.
 
+## Citation
+
+If you use `robot_descriptions.py` in your scientific works, please cite it *e.g.* as follows:
+
+```bibtex
+@software{robot_descriptions_py2024,
+  author = {Caron, Stéphane and Romualdi, Giulio and Kozlov, Lev and Ordonez, Daniel and Tadashi Kussaba, Hugo and Bang, Seung Hyeon},
+  license = {Apache-2.0},
+  month = feb,
+  title = {{robot_descriptions.py: Robot descriptions in Python}},
+  url = {https://github.com/robot-descriptions/robot_descriptions.py},
+  version = {1.8.1},
+  year = {2024}
+}
+```
+
 ## See also
 
 Robot descriptions in other languages: