Fix output examples from dsl reference and ctk feature

Signed-off-by: Yuri Zhao <[email protected]>

Author: yzhao244

ctk/features/call.feature

@@ -22,7 +22,7 @@ Feature: Call Task
             endpoint:
               uri: https://petstore.swagger.io/v2/pet/findByStatus?status={status}
           output:
-            from: .[0]
+            as: .[0]
     """
     And given the workflow input is:
     """yaml
@@ -108,7 +108,7 @@ Feature: Call Task
             parameters:
               status: ${ .status }
           output:
-            from: . | length
+            as: . | length
     """
     And given the workflow input is:
     """yaml

dsl-reference.md

@@ -1515,9 +1515,7 @@ schema:
       petId:
         type: string
     required: [ petId ]
-from:
-  petId: '${ .pet.id }'
-to: '.petList += [ . ]'
+as: '.petList += [ . ]'
 ```
 
 ### Export