docs: add code samples for index and column properties (#212)

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- [x] Appropriate docs were updated
  - `DataFrame.columns`: https://screenshot.googleplex.com/3Bwdb482FBfEsi2
  - `DataFrame.index`: https://screenshot.googleplex.com/4iJymH3FxMn8Hhb
  - `Series.index`: https://screenshot.googleplex.com/7MXQcuASbQ3c8s5 

Fixes internal issue 310260952 🦕

Author: shobsi

third_party/bigframes_vendored/pandas/core/frame.py

@@ -3106,14 +3106,91 @@ def index(self):
         index is used for label-based access and alignment, and can be accessed
         or modified using this attribute.
 
+        **Examples:**
+
+            >>> import bigframes.pandas as bpd
+            >>> bpd.options.display.progress_bar = None
+
+        You can access the index of a DataFrame via ``index`` property.
+
+            >>> df = bpd.DataFrame({'Name': ['Alice', 'Bob', 'Aritra'],
+            ...                     'Age': [25, 30, 35],
+            ...                     'Location': ['Seattle', 'New York', 'Kona']},
+            ...                    index=([10, 20, 30]))
+            >>> df
+                Name  Age  Location
+            10   Alice   25   Seattle
+            20     Bob   30  New York
+            30  Aritra   35      Kona
+            <BLANKLINE>
+            [3 rows x 3 columns]
+            >>> df.index # doctest: +ELLIPSIS
+            <bigframes.core.indexes.index.Index object at ...>
+            >>> df.index.values
+            array([10, 20, 30], dtype=object)
+
+        Let's try setting a new index for the dataframe and see that reflect via
+        ``index`` property.
+
+            >>> df1 = df.set_index(["Name", "Location"])
+            >>> df1
+                            Age
+            Name   Location
+            Alice  Seattle    25
+            Bob    New York   30
+            Aritra Kona       35
+            <BLANKLINE>
+            [3 rows x 1 columns]
+            >>> df1.index # doctest: +ELLIPSIS
+            <bigframes.core.indexes.index.Index object at ...>
+            >>> df1.index.values
+            array([('Alice', 'Seattle'), ('Bob', 'New York'), ('Aritra', 'Kona')],
+                dtype=object)
+
         Returns:
             The index labels of the DataFrame.
         """
         raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
 
     @property
     def columns(self):
-        "The column labels of the DataFrame."
+        """The column labels of the DataFrame.
+
+        **Examples:**
+
+            >>> import bigframes.pandas as bpd
+            >>> bpd.options.display.progress_bar = None
+
+        You can access the column labels of a DataFrame via ``columns`` property.
+
+            >>> df = bpd.DataFrame({'Name': ['Alice', 'Bob', 'Aritra'],
+            ...                     'Age': [25, 30, 35],
+            ...                     'Location': ['Seattle', 'New York', 'Kona']},
+            ...                    index=([10, 20, 30]))
+            >>> df
+                  Name  Age  Location
+            10   Alice   25   Seattle
+            20     Bob   30  New York
+            30  Aritra   35      Kona
+            <BLANKLINE>
+            [3 rows x 3 columns]
+            >>> df.columns
+            Index(['Name', 'Age', 'Location'], dtype='object')
+
+        You can also set new labels for columns.
+
+            >>> df.columns = ["NewName", "NewAge", "NewLocation"]
+            >>> df
+               NewName  NewAge NewLocation
+            10   Alice      25     Seattle
+            20     Bob      30    New York
+            30  Aritra      35        Kona
+            <BLANKLINE>
+            [3 rows x 3 columns]
+            >>> df.columns
+            Index(['NewName', 'NewAge', 'NewLocation'], dtype='object')
+
+        """
         raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
 
     def value_counts(

third_party/bigframes_vendored/pandas/core/series.py

@@ -44,7 +44,54 @@ def struct(self):
 
     @property
     def index(self):
-        """The index (axis labels) of the Series."""
+        """The index (axis labels) of the Series.
+
+        The index of a Series is used to label and identify each element of the
+        underlying data. The index can be thought of as an immutable ordered set
+        (technically a multi-set, as it may contain duplicate labels), and is
+        used to index and align data.
+
+        **Examples:**
+
+            >>> import bigframes.pandas as bpd
+            >>> bpd.options.display.progress_bar = None
+
+        You can access the index of a Series via ``index`` property.
+
+            >>> df = bpd.DataFrame({'Name': ['Alice', 'Bob', 'Aritra'],
+            ...                     'Age': [25, 30, 35],
+            ...                     'Location': ['Seattle', 'New York', 'Kona']},
+            ...                    index=([10, 20, 30]))
+            >>> s = df["Age"]
+            >>> s
+            10    25
+            20    30
+            30    35
+            Name: Age, dtype: Int64
+            >>> s.index # doctest: +ELLIPSIS
+            <bigframes.core.indexes.index.Index object at ...>
+            >>> s.index.values
+            array([10, 20, 30], dtype=object)
+
+        Let's try setting a multi-index case reflect via ``index`` property.
+
+            >>> df1 = df.set_index(["Name", "Location"])
+            >>> s1 = df1["Age"]
+            >>> s1
+            Name    Location
+            Alice   Seattle     25
+            Bob     New York    30
+            Aritra  Kona        35
+            Name: Age, dtype: Int64
+            >>> s1.index # doctest: +ELLIPSIS
+            <bigframes.core.indexes.index.Index object at ...>
+            >>> s1.index.values
+            array([('Alice', 'Seattle'), ('Bob', 'New York'), ('Aritra', 'Kona')],
+                dtype=object)
+
+        Returns:
+            The index labels of the Series.
+        """
         raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
 
     @property