update

docs/tutorials/3_exist_data_new_model.md

@@ -91,7 +91,7 @@ model = dict(
             loss_mask=dict(
                 type='CrossEntropyLoss', use_mask=True, loss_weight=1.0))))
 
-# Set  optimizer
+# Set optimizer
 optimizer = dict(type='SGD', lr=0.01, momentum=0.9, weight_decay=0.0001)
 optimizer_config = dict(grad_clip=None)
 # Set learning policy