add citation paragraph

docs/index.md

@@ -221,6 +221,29 @@ These packages and sites are maintained by third parties. If you install package
 @@
 
 
+## Citing Makie
+
+If you use Makie for a scientific publication, please cite [our JOSS paper](https://joss.theoj.org/papers/10.21105/joss.03349) the following way:
+
+> Danisch & Krumbiegel, (2021). Makie.jl: Flexible high-performance data visualization for Julia. Journal of Open Source Software, 6(65), 3349, https://doi.org/10.21105/joss.03349
+
+You can use the following BibTeX entry:
+
+```
+@article{DanischKrumbiegel2021,
+  doi = {10.21105/joss.03349},
+  url = {https://doi.org/10.21105/joss.03349},
+  year = {2021},
+  publisher = {The Open Journal},
+  volume = {6},
+  number = {65},
+  pages = {3349},
+  author = {Simon Danisch and Julius Krumbiegel},
+  title = {Makie.jl: Flexible high-performance data visualization for Julia},
+  journal = {Journal of Open Source Software}
+}
+```
+
 ## Getting Help
 
 1. Use the REPL `?` help mode.