text: Title: ENH: Passing a single value to `.describe(percentiles = [0.25])` returns 25th- and 50th-percentile
  Body: ### Pandas version checks
  
  - [X] I have checked that this issue has not already been reported.
  
  - [X] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas.
  
  - [X] I have confirmed this bug exists on the [main branch](https://pandas.pydata.org/docs/dev/getting_started/install.html#installing-the-development-version-of-pandas) of pandas.
  
  
  ### Reproducible Example
  
  ```python
  import numpy as np
  import pandas as pd
  
  # creating a single series dataframe
  frame = pd.DataFrame(np.array([1, 2, 3, 4, 5, 100]))
  
  # getting the describe with single percentile value
  frame.describe(percentiles = [0.25])
  ```
  
  
  ### Issue Description
  
  Using a single percentile value below 50 for `percentiles` for data frame describe function returns 50th percentile data by default, while the same is not reflected when the value is more than 50.
  
  ```python
  # considering the above dataframe in example
  >>> frame.describe(percentiles = [0.25])
                  0
  count    6.000000
  mean    19.166667
  std     39.625329
  min      1.000000
  25%      2.250000
  50%      3.500000
  max    100.000000
  >>> frame.describe(percentiles = [0.35])
                  0
  count    6.000000
  mean    19.166667
  std     39.625329
  min      1.000000
  35%      2.750000
  50%      3.500000
  max    100.000000
  >>> frame.describe(percentiles = [0.51])
                  0
  count    6.000000
  mean    19.166667
  std     39.625329
  min      1.000000
  50%      3.500000
  51%      3.550000
  max    100.000000
  ```
  
  ### Expected Behavior
  
  Should return only given percentile value instead.
  
  ### Installed Versions
  
  <details>
  
  INSTALLED VERSIONS
  ------------------
  commit                : 0691c5cf90477d3503834d983f69350f250a6ff7
  python                : 3.12.4
  python-bits           : 64
  OS                    : Windows
  OS-release            : 10
  Version               : 10.0.19045
  machine               : AMD64
  processor             : Intel64 Family 6 Model 140 Stepping 2, GenuineIntel
  byteorder             : little
  LC_ALL                : None
  LANG                  : None
  LOCALE                : English_India.1252
  
  pandas                : 2.2.3
  numpy                 : 2.2.0
  pytz                  : 2024.2
  dateutil              : 2.9.0.post0
  pip                   : 24.1
  Cython                : None
  sphinx                : None
  IPython               : None
  adbc-driver-postgresql: None
  adbc-driver-sqlite    : None
  bs4                   : None
  blosc                 : None
  bottleneck            : None
  dataframe-api-compat  : None
  fastparquet           : None
  fsspec                : None
  html5lib              : None
  hypothesis            : None
  gcsfs                 : None
  jinja2                : None
  lxml.etree            : None
  matplotlib            : None
  numba                 : None
  numexpr               : None
  odfpy                 : None
  openpyxl              : None
  pandas_gbq            : None
  psycopg2              : None
  pymysql               : None
  pyarrow               : None
  pyreadstat            : None
  pytest                : None
  python-calamine       : None
  pyxlsb                : None
  s3fs                  : None
  scipy                 : None
  sqlalchemy            : None
  tables                : None
  tabulate              : None
  xarray                : None
  xlrd                  : None
  xlsxwriter            : None
  zstandard             : None
  tzdata                : 2024.2
  qtpy                  : None
  pyqt5                 : None
  
  </details>
  