Improve docs for scratch directive (#6356)

See discussion: https://community.seqera.io/t/nextflow-process-directive-scratch-cleans-but-does-not-remove-scratch-dir/2337

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Signed-off-by: Phil Ewels <[email protected]>
Signed-off-by: Ben Sherman <[email protected]>
Co-authored-by: Ben Sherman <[email protected]>
Co-authored-by: Chris Hakkaart <[email protected]>

Author: 3 people

docs/reference/process.md

@@ -1446,6 +1446,8 @@ process hello {
 
 By doing this, it tries to execute the script in the directory defined by the variable `$TMPDIR` in the execution node. If this variable does not exist, it will create a new temporary directory by using the Linux command `mktemp`.
 
+Nextflow creates a subdirectory within the scratch directory for each task and automatically deletes it once the task completes.
+
 :::{note}
 Cloud-based executors use `scratch = true` by default, since the work directory resides in object storage.
 :::