Add Makie.jl as reference

README.md

-# RainbowAlga
+# RainbowAlga.jl
 
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://tgal.gitlab.io/RainbowAlga.jl/dev)
 [![Build Status](https://git.km3net.de/tgal/RainbowAlga.jl/badges/main/pipeline.svg)](https://git.km3net.de/tgal/RainbowAlga.jl/pipelines)
 [![Coverage](https://git.km3net.de/tgal/RainbowAlga.jl/badges/main/coverage.svg)](https://git.km3net.de/tgal/RainbowAlga.jl/commits/main)
 
+The `RainbowAlga.jl` package is an interactive 3D display which visualises events in water and ice Cherenkov neutrino telescopes. The underlying engine is [`Makie.jl`](https://doi.org/10.5281/zenodo.3735092).
+
 ## Installation
 
 `RainbowAlga.jl` is not an officially registered Julia package but it's available via