Add note on xenium explorer

Author: quentinblampey

README.md

@@ -1,6 +1,8 @@
 # SpatialData to Xenium Explorer
 Converting any [`SpatialData`](https://github.com/scverse/spatialdata) object into files that can be open by the [Xenium Explorer](https://www.10xgenomics.com/support/software/xenium-explorer).
 
+> *Xenium Explorer* is a registered trademark of 10x Genomics
+
 ## Installation
 
 This package is currently in development. You can test it out, but you may experience some issues.