Add citation metadata

.github/CITATION.cff

@@ -0,0 +1,33 @@
+cff-version: 1.2.0
+title: >-
+  ALNS: a Python implementation of the adaptive large
+  neighbourhood search metaheuristic
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+authors:
+  - given-names: Niels A.
+    family-names: Wouda
+    email: [email protected]
+    affiliation: University of Groningen
+    orcid: 'https://orcid.org/0000-0003-2463-0309'
+  - given-names: Leon
+    family-names: Lan
+    email: [email protected]
+    affiliation: Vrije Universiteit Amsterdam
+    orcid: 'https://orcid.org/0000-0001-7479-0218'
+identifiers:
+  - type: doi
+    value: 10.21105/joss.05028
+repository-code: 'https://github.com/N-Wouda/ALNS'
+journal: Journal of Open Source Software
+number: 81
+volume: 8
+pages: 5028
+publisher: The Open Journal
+keywords:
+  - operations research
+  - metaheuristics
+  - adaptive large neighbourhood search
+license: MIT

README.md

@@ -2,6 +2,7 @@
 [![ALNS](https://github.com/N-Wouda/ALNS/actions/workflows/alns.yaml/badge.svg)](https://github.com/N-Wouda/ALNS/actions/workflows/alns.yaml)
 [![Documentation Status](https://readthedocs.org/projects/alns/badge/?version=latest)](https://alns.readthedocs.io/en/latest/?badge=latest)
 [![codecov](https://codecov.io/gh/N-Wouda/ALNS/branch/master/graph/badge.svg)](https://codecov.io/gh/N-Wouda/ALNS)
+[![DOI](https://joss.theoj.org/papers/10.21105/joss.05028/status.svg)](https://doi.org/10.21105/joss.05028)
 
 ``alns`` is a general, well-documented and tested implementation of the adaptive
 large neighbourhood search (ALNS) metaheuristic in Python. ALNS is an algorithm
@@ -74,6 +75,32 @@ one!
 
 If you are looking for help, please follow the instructions [here][7].
 
+### How to cite `alns`
+
+If you use `alns` in your research, please consider citing the following paper:
+
+> Wouda, N.A., and L. Lan (2023). 
+> ALNS: a Python implementation of the adaptive large neighbourhood search metaheuristic. 
+> _Journal of Open Source Software_, 8(81): 5028. 
+> https://doi.org/10.21105/joss.05028
+
+Or, using the following BibTeX entry:
+
+```bibtex
+@article{Wouda_Lan_ALNS_2023, 
+  doi = {10.21105/joss.05028}, 
+  url = {https://doi.org/10.21105/joss.05028}, 
+  year = {2023}, 
+  publisher = {The Open Journal}, 
+  volume = {8}, 
+  number = {81}, 
+  pages = {5028}, 
+  author = {Niels A. Wouda and Leon Lan}, 
+  title = {ALNS: a Python implementation of the adaptive large neighbourhood search metaheuristic}, 
+  journal = {Journal of Open Source Software} 
+}
+```
+
 [1]: https://alns.readthedocs.io/en/latest/
 
 [2]: https://alns.readthedocs.io/en/latest/examples/travelling_salesman_problem.html