DOC: add the default median behavior in function docstring

Author: ZenithClown

pandas/core/generic.py

@@ -10795,7 +10795,8 @@ def describe(
             The percentiles to include in the output. All should
             fall between 0 and 1. The default is
             ``[.25, .5, .75]``, which returns the 25th, 50th, and
-            75th percentiles.
+            75th percentiles. If a blank list is passed, then returns
+            only the 50th percentile value.
         include : 'all', list-like of dtypes or None (default), optional
             A white list of data types to include in the result. Ignored
             for ``Series``. Here are the options:

pandas/core/methods/describe.py

@@ -74,7 +74,8 @@ def describe_ndframe(
     percentiles : list-like of numbers, optional
         The percentiles to include in the output. All should fall between 0 and 1.
         The default is ``[.25, .5, .75]``, which returns the 25th, 50th, and
-        75th percentiles.
+        75th percentiles.If a blank list is passed, then returns only the
+        50th percentile value.
 
     Returns
     -------