Fix doc bug workflow (#19269)

Co-authored-by: liuwangwang <liuwangwang@hikvision.com.cn>

web/app/components/develop/template/template_workflow.en.mdx

@@ -90,7 +90,7 @@ Workflow applications offers non-session support and is ideal for translation, a
     Each streaming chunk starts with `data:`, separated by two newline characters `\n\n`, as shown below:
     <CodeGroup>
     ```streaming {{ title: 'Response' }}
-    data: {"event": "message", "task_id": "900bbd43-dc0b-4383-a372-aa6e6c414227", "id": "663c5084-a254-4040-8ad3-51f2a3c1a77c", "answer": "Hi", "created_at": 1705398420}\n\n
+    data: {"event": "text_chunk", "workflow_run_id": "b85e5fc5-751b-454d-b14e-dc5f240b0a31", "task_id": "bd029338-b068-4d34-a331-fc85478922c2", "data": {"text": "\u4e3a\u4e86", "from_variable_selector": ["1745912968134", "text"]}}\n\n
     ```
     </CodeGroup>
     The structure of the streaming chunks varies depending on the `event`:
@@ -116,6 +116,13 @@ Workflow applications offers non-session support and is ideal for translation, a
         - `predecessor_node_id` (string) optional Prefix node ID, used for canvas display execution path
         - `inputs` (object) Contents of all preceding node variables used in the node
         - `created_at` (timestamp) timestamp of start, e.g., 1705395332
+    - `event: text_chunk` Text fragment  
+      - `task_id` (string) Task ID, used for request tracking and the below Stop Generate API 
+      - `workflow_run_id` (string) Unique ID of workflow execution 
+      - `event` (string) fixed to `text_chunk`
+      - `data` (object) detail
+        - `text` (string) Text content
+        - `from_variable_selector` (array) Text source path, helping developers understand which node and variable generated the text
     - `event: node_finished` node execution ends, success or failure in different states in the same event
       - `task_id` (string) Task ID, used for request tracking and the below Stop Generate API
       - `workflow_run_id` (string) Unique ID of workflow execution