docs: add progress_bar code sample (#508)

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Fixes #<issue_number_goes_here> 🦕

third_party/bigframes_vendored/pandas/core/config_init.py

@@ -32,9 +32,21 @@
 User can execute the job by calling .to_pandas()
     >>> # df.to_pandas()
 
-Reset option
+Reset repr_mode option
     >>> bpd.options.display.repr_mode = "head"
 
+Can also set the progress_bar option to see the progress bar in terminal,
+    >>> bpd.options.display.progress_bar = "terminal"
+
+notebook,
+    >>> bpd.options.display.progress_bar = "notebook"
+
+or just remove it.
+    >>> bpd.options.display.progress_bar = None
+
+Setting to default value "auto" will detect and show progress bar automatically.
+    >>> bpd.options.display.progress_bar = "auto"
+
 Attributes:
     max_columns (int, default 20):
         If `max_columns` is exceeded, switch to truncate view.