Add conference paper citation (#1170)

CITATION.cff

@@ -1,5 +1,6 @@
 cff-version: 1.2.0
 title: DLA-Future 0.6.0
+repository-code: https://github.com/eth-cscs/DLA-Future
 message: >-
   If you use this software, please cite it using the
   metadata from this file.
@@ -52,5 +53,6 @@ keywords:
   - "linear algebra"
   - mpi
 license: BSD-3-Clause
+license-url: https://opensource.org/license/bsd-3-clause
 version: 0.6.0
 date-released: '2024-06-24'

README.md

@@ -43,6 +43,32 @@ target_link_libraries(<your_target> PRIVATE DLAF::DLAF)
 
 See [DOCUMENTATION.md](DOCUMENTATION.md) for the documentation of older versions, or for the instructions to build it.
 
+## Citing
+
+If you are using DLA-Future, please cite the following paper in addition to this repository:
+
+```
+@InProceedings{10.1007/978-3-031-61763-8_13,
+    author="Solc{\`a}, Raffaele
+        and Simberg, Mikael
+        and Meli, Rocco
+        and Invernizzi, Alberto
+        and Reverdell, Auriane
+        and Biddiscombe, John",
+    editor="Diehl, Patrick
+        and Schuchart, Joseph
+        and Valero-Lara, Pedro
+        and Bosilca, George",
+    title="DLA-Future: A Task-Based Linear Algebra Library Which Provides a GPU-Enabled Distributed Eigensolver",
+    booktitle="Asynchronous Many-Task Systems and Applications",
+    year="2024",
+    publisher="Springer Nature Switzerland",
+    address="Cham",
+    pages="135--141",
+    isbn="978-3-031-61763-8"
+}
+```
+
 ## Acknowledgements
 
 The development of DLAF library would not be possible without support of the following organizations (in alphabetic order):