Add showOutput option to docs

docs/Custom_Command_Keybindings.md

@@ -77,6 +77,7 @@ For a given custom command, here are the allowed fields:
 | loadingText | text to display while waiting for command to finish | no |
 | description | text to display in the keybindings menu that appears when you press 'x' | no |
 | stream | whether you want to stream the command's output to the Command Log panel | no |
+| showOutput | whether you want to show the command's output in a gui prompt | no |
 
 ### Contexts
 
@@ -159,7 +160,7 @@ If your custom keybinding collides with an inbuilt keybinding that is defined fo
 
 ### Debugging
 
-If you want to verify that your command actually does what you expect, you can wrap it in an 'echo' call and set `subprocess: true` so that it doesn't actually execute the command but you can see how the placeholders were resolved. Alternatively you can run lazygit in debug mode with `lazygit --debug` and in another terminal window run `lazygit --logs` to see which commands are actually run
+If you want to verify that your command actually does what you expect, you can wrap it in an 'echo' call and set `showOutput: true` so that it doesn't actually execute the command but you can see how the placeholders were resolved. Alternatively you can run lazygit in debug mode with `lazygit --debug` and in another terminal window run `lazygit --logs` to see which commands are actually run
 
 ### More Examples