Add deprecation notice

Signed-off-by: Paolo Di Tommaso <[email protected]>

Author: pditommaso

README.md

@@ -11,6 +11,9 @@ NOTE: If you want to use this project as a starting point for a custom plugin, y
 
 See the [Nextflow documentation](https://nextflow.io/docs/latest/plugins.html) for more information about developing plugins.
 
+> [!IMPORTANT]
+> This plugin has been deprecated in favour of the new Nextflow command `nextflow plugin create` and template project [nf-plugin-template](https://github.com/nextflow-io/nf-plugin-template). 
+
 ## Plugin structure
                     
 - `settings.gradle`