[SPARK-28031][PYSPARK][TEST] Improve doctest on over function of Column

## What changes were proposed in this pull request?

Just found the doctest on `over` function of `Column` is commented out. The window spec is also not for the window function used there.

We should either remove the doctest, or improve it.

Because other functions of `Column` have doctest generally, so this PR tries to improve it.

## How was this patch tested?

Added doctest.

Closes #24854 from viirya/column-test-minor.

Authored-by: Liang-Chi Hsieh <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: viirya

python/pyspark/sql/column.py

@@ -668,9 +668,17 @@ def over(self, window):
         :return: a Column
 
         >>> from pyspark.sql import Window
-        >>> window = Window.partitionBy("name").orderBy("age").rowsBetween(-1, 1)
+        >>> window = Window.partitionBy("name").orderBy("age") \
+                .rowsBetween(Window.unboundedPreceding, Window.currentRow)
         >>> from pyspark.sql.functions import rank, min
-        >>> # df.select(rank().over(window), min('age').over(window))
+        >>> df.withColumn("rank", rank().over(window)) \
+                .withColumn("min", min('age').over(window)).show()
+        +---+-----+----+---+
+        |age| name|rank|min|
+        +---+-----+----+---+
+        |  5|  Bob|   1|  5|
+        |  2|Alice|   1|  2|
+        +---+-----+----+---+
         """
         from pyspark.sql.window import WindowSpec
         if not isinstance(window, WindowSpec):