Merge pull request #20 from Bonnarel/main

Update README.md

README.md

@@ -3,5 +3,7 @@
   * Authors : François Bonnarel, Mireille Louys, Baptiste Cecconi, Vincenzo Galluzzi, Yan Grange,  Mark Kettenis, Mark Lacy, Alan Loh, Mattia Mancini, Peter Teuben, Alessandra Zanichelli
   * Abstract : This is a proposed extension to the Obscore specification for description of radio (including visibility and single dish) data
 
+Previous version of the project available in the legacy repository https://github.com/ivoa/ObsCoreExtensionForVisibilityData
 
-[![PDF-Preview](https://img.shields.io/badge/Preview-PDF-blue)](../../releases/download/auto-pdf-preview/ObsCoreExtensionForVisibilityData-draft.pdf)
+
+[![PDF-Preview](https://img.shields.io/badge/Preview-PDF-blue)](../../releases/download/auto-pdf-preview/ObsCoreExtensionForRadioData-draft.pdf)