Merge pull request #503 from nextflow-io/add_deprec_when

Add deprecation warning for when clause

Author: ewels

docs/basic_training/processes.md

@@ -1026,6 +1026,10 @@ workflow {
 
 The `when` declaration allows you to define a condition that must be verified in order to execute the process. This can be any expression that evaluates a boolean value.
 
+!!! warning
+
+    Deprecated since version 24.10.0: Use conditional logic (e.g. `if` statement, [filter](https://www.nextflow.io/docs/latest/reference/operator.html#operator-filter) operator) in the calling workflow instead.
+
 It is useful to enable/disable the process execution depending on the state of various inputs and parameters. For example:
 
 ```groovy linenums="1" title="snippet.nf"