Update gb25.md

Added g202

Author: jpcoles-cscs

docs/guides/gb25.md

@@ -18,6 +18,7 @@ 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 |
+| `g202` | 08-21| 16:00 | 1            | GB run |
 
 ## System