gui: correct documentation for new worst path image TCL command

Signed-off-by: Augusto Berndt <[email protected]>

Author: gudeh

src/gui/README.md

@@ -951,15 +951,14 @@ Update the paths in the Timing Report widget and select the path with the worst
 
 ```tcl
 gui::show_worst_path
-    [-setup|-hold]
+    [setup]
 ```
 
 #### Options
 
 | Switch Name | Description |
 | ---- | ---- |
-| `-setup` | Select the path with the worst setup slack (default). |
-| `-hold` | Select the path with the worst hold slack. |
+| `setup` | Boolean (default true) to select worst setup slack path. If false, selects worst hold slack path. |
 
 ### Clear Timing Path