DOC:Updated as suggested in the comments of PR#20211
- [x] PR title is "DOC: update the docstring"
- [x] closes #20211 
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

The following is added for the doc string :
         """
	Return a boolean if this key is in the index.

         Parameters
         ----------
         key : object
         key to be searched.

         Returns
         -------
         boolean
         result of the search.

         See Also
         --------
         Index.isin

         Examples
         --------
         >>> pd.CategoricalIndex([2000, 2001, 2012]).contains(2001)
         True
         >>> pd.CategoricalIndex([2000, 2001, 2012]).contains(2222)
         False
         """

The suggestions mentioned in the pull request#20211 were followed. Probably this can help close pull request#20211.
Hello @ksasi! Thanks for updating the PR.

 - There are no PEP8 issues in the file [`pandas/core/indexes/base.py`](https://github.com/ksasi/pandas/blob/51f853956302c98ffa7f78ddfbf3d5a3c5b5ddab/pandas/core/indexes/base.py) !



##### Comment last updated on October 08, 2018 at 09:04 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=h1) Report
> Merging [#23039](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/ce1f81f8bcf038072e0ecb661310984076c4e7de?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23039/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23039   +/-   ##
=======================================
  Coverage   92.19%   92.19%           
=======================================
  Files         169      169           
  Lines       50873    50873           
=======================================
  Hits        46904    46904           
  Misses       3969     3969
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.61% <ø> (ø)` | :arrow_up: |
| #single | `42.32% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/indexes/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/23039/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9iYXNlLnB5) | `96.54% <ø> (ø)` | :arrow_up: |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=footer). Last update [ce1f81f...51f8539](https://codecov.io/gh/pandas-dev/pandas/pull/23039?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Sorry about it @ksasi, but @Tanya-Jain has been working with me in the final changes for this PR during the sprint, and she's got very good work that she will be submitting soon. I know it's frustraiting to have to discard work, but we need to be more careful on avoiding overlap. Try checking the last comments of the issue (or PR) and make sure nobody said is already working on it.

Hope to see you tomorrow in the sprint, and let's see if we can coordinate better then. :) sure, np @datapythonista .Thanks for letting me know, I will try to work on any other open/pending items that might help.