update quant_post api doc

paddleslim/quant/quanter.py

@@ -214,15 +214,14 @@ def quant_post(executor,
             fluid.io.save_inference_model.
         sample_generator(Python Generator): The sample generator provides 
             calibrate data for DataLoader, and it only returns a sample every time.
-        model_filename(str, optional): The name of model file to load the inference 
-                program. If parameters are saved in separate files, 
-                set it as 'None'. Default is 'None'.
-        params_filename(str, optional): The name of params file to load all parameters.
+        model_filename(str, optional): The name of model file. If parameters 
+            are saved in separate files, set it as 'None'. Default is 'None'.
+        params_filename(str, optional): The name of params file.
                 When all parameters are saved in a single file, set it 
                 as filename. If parameters are saved in separate files, 
                 set it as 'None'. Default is 'None'.
         batch_size(int, optional): The batch size of DataLoader, default is 16.
-        batch_nums(int, optional): If set batch_nums, the number of calibrate 
+        batch_nums(int, optional): If batch_nums is not None, the number of calibrate 
                         data is 'batch_size*batch_nums'. If batch_nums is None, use all data
                         generated by sample_generator  as calibrate data.
         scope(fluid.Scope, optional): The scope to run program, use it to load