docs(design): explain individual lines of input ex

docs/design/iowo-design.typ

@@ -69,9 +69,9 @@ The foundation of actually "doing" something.
 - So all of these are equivalent:
 
 ```iowo
-1 | add 2
-add 1 2
-[ 1 2 ] | add
+add 1 2        -- all inputs as arguments
+[ 1 2 ] | add  -- all inputs through the pipeline
+1 | add 2      -- one input through the pipeline, one as argument
 ```
 
 ==== Outputs