CommandLineTool.arguments doc clarification

Author: wgerlach

CommandLineTool.yml

@@ -639,7 +639,10 @@ $graph:
         "_container": "@list"
     - name: arguments
       doc: |
-        Command line bindings which are not directly associated with input parameters.
+        Command line bindings which are not directly associated with input
+        parameters. If the value is a string, it is used as a string literal
+        argument. If it is an Expression, the result of the evaluation is used
+        as an argument.
       type:
         - "null"
         - type: array