docs(features): note Edit > Data shows only in data file windows (#6)

Author: datlechin

features/data-files.mdx

@@ -92,7 +92,7 @@ Right-click a column header, or use the **Columns** menu in the toolbar, to rena
 
 ## Clean up data
 
-These commands are on **Edit > Data** and on the column header's context menu. With a whole column selected they change every visible row; with cells selected they change only those cells. Each one is a single undo step.
+These commands are on **Edit > Data** and on the column header's context menu. **Edit > Data** appears only while a data file window is in front. With a whole column selected they change every visible row; with cells selected they change only those cells. Each one is a single undo step.
 
 | Command | Does |
 |---|---|