Add term 'workflow introspection' to docs

I keep searching for this specific term and it's been removed. Apparently I wasn't the only one.

Signed-off-by: Phil Ewels <phil.ewels@seqera.io>

docs/reference/stdlib.md

@@ -10,7 +10,7 @@ This page describes the built-in constants, functions, and types provided by Nex
 
 ### Constants
 
-The following constants are globally available in a Nextflow script:
+The following constants are globally available in a Nextflow script for workflow introspection:
 
 `baseDir`
 : :::{deprecated} 20.04.0