Update new-project.rst (Lightning-AI#1655)

fix a typo

Author: weipengOO98

docs/source/new-project.rst

@@ -100,7 +100,7 @@ To also add a validation loop add the following functions
         def validation_epoch_end(self, outputs):
             avg_loss = torch.stack([x['val_loss'] for x in outputs]).mean()
             tensorboard_logs = {'val_loss': avg_loss}
-            return {'val_loss': avg_loss, 'log': tensorboard_logs
+            return {'val_loss': avg_loss, 'log': tensorboard_logs}
 
         def val_dataloader(self):
             # TODO: do a real train/val split