[DOCS] Add script note to nested query docs (#77431) (#78701)

As the script has only access to the nested document, this should be
documented.

Co-authored-by: James Rodewig <[email protected]>

Co-authored-by: Alexander Reelsen <[email protected]>

Author: jrodewig

docs/reference/query-dsl/nested-query.asciidoc

@@ -121,6 +121,12 @@ field `path`.
 [[nested-query-notes]]
 ==== Notes
 
+[[nested-query-script-notes]]
+===== Context of script queries
+If you run a <<query-dsl-script-query,`script` query>> within a nested query,
+you can only access doc values from the nested document, not the parent
+or root document.
+
 [[multi-level-nested-query-ex]]
 ===== Multi-level nested queries