Create workflow sub workflows (#36)

Adding sub workflows to admin workflow create request

flyteidl/gen/pb-go/flyteidl/service/admin.swagger.json

@@ -4013,6 +4013,13 @@
         "template": {
           "$ref": "#/definitions/coreWorkflowTemplate",
           "description": "Template of the task that encapsulates all the metadata of the workflow."
+        },
+        "sub_workflows": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/coreWorkflowTemplate"
+          },
+          "description": "Workflows that are embedded into other workflows need to be passed alongside the parent workflow to the\npropeller compiler (since the compiler doesn't have any knowledge of other workflows - ie, it doesn't reach out\nto Admin to see other registered workflows).  In fact, subworkflows do not even need to be registered."
         }
       },
       "description": "Represents a structure that encapsulates the specification of the workflow."

flyteidl/gen/pb-go/flyteidl/service/flyteadmin/api/swagger.yaml

@@ -16672,6 +16672,15 @@ definitions:
         description: "Template of the task that encapsulates all the metadata of the\
           \ workflow."
         $ref: "#/definitions/coreWorkflowTemplate"
+      sub_workflows:
+        type: "array"
+        description: "Workflows that are embedded into other workflows need to be\
+          \ passed alongside the parent workflow to the\npropeller compiler (since\
+          \ the compiler doesn't have any knowledge of other workflows - ie, it doesn't\
+          \ reach out\nto Admin to see other registered workflows).  In fact, subworkflows\
+          \ do not even need to be registered."
+        items:
+          $ref: "#/definitions/coreWorkflowTemplate"
     description: "Represents a structure that encapsulates the specification of the\
       \ workflow."
   coreAlias: