Update gb25.md (#225)

Removed second window for cwd01 per request from MGG.

Author: jpcoles-cscs

docs/guides/gb25.md

@@ -18,7 +18,6 @@ Times are in CEST (Central European  Time): [Time conversion table](https://time
 | `cwd01`| 08-20| 18:00 | 5            | GB run |
 | -      | 08-20| 23:00 | 9            | *free slot* |
 | `g188` | 08-21| 08:00 | 8            | GB run |
-| `cwd01`| 08-21| 16:00 | 5            | GB run |
 
 ## System