[scripts.generate_saliencymaps] Fix usage docs

src/ptbench/scripts/generate_saliencymaps.py

@@ -27,7 +27,7 @@ logger = setup(__name__.split(".")[0], format="%(levelname)s: %(message)s")
 
    .. code:: sh
 
-      ptbench generate-saliencymaps -vv densenet tbx11k-v1-healthy-vs-atb --weight=path/to/model_final.pth --output-folder=path/to/output
+      ptbench generate-saliencymaps -vv densenet tbx11k-v1-healthy-vs-atb --weight=path/to/model_final.ckpt --output-folder=path/to/output
 
 """,
 )