Fix docstring (#2884)

* Fix docstring

"mean absolute loss" rather than "root mean absolute loss"

* minor docstring fix

Co-authored-by: rohitgr7 <rohitgr1998@gmail.com>

pytorch_lightning/callbacks/base.py

@@ -47,11 +47,11 @@ class Callback(abc.ABC):
         pass
 
     def on_train_batch_start(self, trainer, pl_module, batch, batch_idx, dataloader_idx):
-        """Called when the validation batch begins."""
+        """Called when the train batch begins."""
         pass
 
     def on_train_batch_end(self, trainer, pl_module, batch, batch_idx, dataloader_idx):
-        """Called when the validation batch ends."""
+        """Called when the train batch ends."""
         pass
 
     def on_train_epoch_start(self, trainer, pl_module):

pytorch_lightning/metrics/regression.py

@@ -101,7 +101,7 @@ class RMSE(Metric):
 
 class MAE(Metric):
     """
-    Computes the root mean absolute loss or L1-loss.
+    Computes the mean absolute loss or L1-loss.
 
     Example: