docs: Fix the DataFrame.apply code sample (#366)

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Fixes #<issue_number_goes_here> 🦕

Author: shobsi

third_party/bigframes_vendored/pandas/core/frame.py

@@ -3296,19 +3296,19 @@ def apply(self, func, *, args=(), **kwargs):
 
             >>> df = bpd.DataFrame({'col1': [1, 2], 'col2': [3, 4]})
             >>> df
-            col1	col2
-            0	1	3
-            1	2	4
+               col1  col2
+            0     1     3
+            1     2     4
             <BLANKLINE>
             [2 rows x 2 columns]
 
-            >>> def sqaure(x):
+            >>> def square(x):
             ...     return x * x
-            >>> df1 = df.apply(sqaure)
-            >>> df
+
+            >>> df.apply(square)
                col1  col2
-            0     1     3
-            1     2     4
+            0     1     9
+            1     4    16
             <BLANKLINE>
             [2 rows x 2 columns]