Add Automatic Mixed Precision option for training and evaluation. (#199)

lerobot/configs/default.yaml

@@ -10,6 +10,9 @@ hydra:
     name: default
 
 device: cuda  # cpu
+# `use_amp` determines whether to use Automatic Mixed Precision (AMP) for training and evaluation. With AMP,
+# automatic gradient scaling is used.
+use_amp: false
 # `seed` is used for training (eg: model initialization, dataset shuffling)
 # AND for the evaluation environments.
 seed: ???