`FITLER` => `FILTER` (#720)

docs/en_US/sqls/windows.md

@@ -125,7 +125,7 @@ In some cases, not all the inputs are needed for the window. Filter clause is pr
 
 The filter clause must follow the window function. The filter clause must be like `FILTER(WHERE expr)`. Example:
 ```sql
-SELECT * FROM demo GROUP BY COUNTWINDOW(3,1) FITLER(where revenue > 100)
+SELECT * FROM demo GROUP BY COUNTWINDOW(3,1) FILTER(where revenue > 100)
 ```
 
 ## Timestamp Management
@@ -143,4 +143,4 @@ CREATE STREAM demo (
 In event time mode, the watermark algorithm is used to calculate a window.
 
 ## Runtime error in window
-If the window receive an error (for example, the data type does not comply to the stream definition) from upstream, the error event will be forwarded immediately to the sink. The current window calculation will ignore the error event.
+If the window receive an error (for example, the data type does not comply to the stream definition) from upstream, the error event will be forwarded immediately to the sink. The current window calculation will ignore the error event.