docs: update 06-stream.md to correct sample sql statement

the existing sql statement failed due to invalid syntax on "select _wstart as start". copying the statement from the zh document instead

docs/en/07-develop/06-stream.md

@@ -52,7 +52,7 @@ CREATE TABLE d1004 USING meters TAGS ("California.LosAngeles", 3);
 ### Create a Stream
 
 ```sql
-create stream current_stream into current_stream_output_stb as select _wstart as start, _wend as end, max(current) as max_current from meters where voltage <= 220 interval (5s);
+create stream current_stream trigger at_once into current_stream_output_stb as select _wstart as wstart, _wend as wend, max(current) as max_current from meters where voltage <= 220 interval (5s);
 ```
 
 ### Write Data