Update 14-stream.md

docs/en/12-taos-sql/14-stream.md

@@ -149,7 +149,7 @@ In both of these methods, configuring the watermark is essential for obtaining a
 
 All [scalar functions](../function/#scalar-functions) are available in stream processing.
 All System Information Functions are <b>not</b> available for stream processing.
-All aggregate and selection functions are available in stream processing, except following functions
+All [aggregate and selection functions](../function/#system-information-functions) are available in stream processing, except following functions
 
 - [leastsquares](../function/#leastsquares)
 - [percentile](../function/#percentile)