Add CITATION file and update README with citation info

CITATION.cff

@@ -0,0 +1,28 @@
+cff-version: "1.2.0"
+authors:
+- family-names: Magri
+  given-names: Victor A. P.
+  orcid: "https://orcid.org/0000-0002-3389-523X"
+doi: 10.5281/zenodo.11657386
+message: If you use this software, please cite our article in the
+  Journal of Open Source Software.
+preferred-citation:
+  authors:
+  - family-names: Magri
+    given-names: Victor A. P.
+    orcid: "https://orcid.org/0000-0002-3389-523X"
+  date-published: 2024-06-24
+  doi: 10.21105/joss.06654
+  issn: 2475-9066
+  issue: 98
+  journal: Journal of Open Source Software
+  publisher:
+    name: Open Journals
+  start: 6654
+  title: "Hypredrive: High-level interface for solving linear systems
+    with hypre"
+  type: article
+  url: "https://joss.theoj.org/papers/10.21105/joss.06654"
+  volume: 9
+title: "*Hypredrive*: High-level interface for solving linear systems
+  with *hypre*"

README.md

@@ -1,3 +1,5 @@
+[![DOI](https://joss.theoj.org/papers/10.21105/joss.06654/status.svg)](https://doi.org/10.21105/joss.06654)
+
 # *hypredrive*
 
 High-level interface for solving linear systems with hypre, providing a user-friendly way to leverage its functionalities. Key features are:
@@ -44,6 +46,18 @@ Check *hypredrive*'s manual [here](https://hypredrive.readthedocs.io/en/latest/)
 Please read [CONTRIBUTING](CONTRIBUTING.md) for details on contributing to *hypredrive*,
 including the process for submitting pull requests to us.
 
+## Citing
+
+If you are referencing *hypredrive* in a publication, please cite the following paper:
+
+    Magri, V. A. P. (2024). Hypredrive: High-level interface for solving linear systems
+    with hypre. Journal of Open Source Software,
+    9(98), 6654. https://doi.org/10.21105/joss.06654
+
+You can easily obtain the citation in APA or BibTeX format directly from GitHub. Navigate
+to the "Cite this repository" option located in the "About" section. Additionally, you can
+find the raw BibTeX format in the comments section of the [CITATION](CITATION.cff) file.
+
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for