Update citation

Author: pierotofy

src/content/docs/index.mdx

@@ -49,4 +49,19 @@ WebODM is licensed under the terms of the [GNU Affero General Public License v3.
 
 ## Trademark
 
-See [Trademark Guidelines](https://github.com/WebODM/WebODM/blob/master/TRADEMARK.md)
+See [Trademark Guidelines](https://github.com/WebODM/WebODM/blob/master/TRADEMARK.md)
+
+## Citation
+
+```
+@software{WebODM,
+  author = {Toffanin, Piero and {WebODM Contributors}},
+  doi = {10.5281/zenodo.3965771},
+  title = {{WebODM: User-friendly, commercial-grade software for processing aerial imagery.}},
+  url = {https://github.com/WebODM/WebODM}
+}
+```
+
+```
+Toffanin, P., & WebODM Contributors. WebODM: User-friendly, commercial-grade software for processing aerial imagery. [Computer software]. https://doi.org/10.5281/zenodo.3965771
+```