Add deprecation notice

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

Author: pditommaso

README.md

@@ -1,5 +1,8 @@
 # nf-hello plugin 
- 
+
+> [!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). 
+
 This project contains a simple Nextflow plugin called `nf-hello` which provides examples of different plugin extensions:
 
 - A custom trace observer that prints a message when the workflow starts and when the workflow completes
@@ -11,6 +14,7 @@ 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.
 
+
 ## Plugin structure
                     
 - `settings.gradle`