DOC: fix code-block in the reshaping docs
- [x] closes #28819


When I review file It looks fixed but checks failing :cry: 
https://github.com/pandas-dev/pandas/pull/28838/files?short_path=47c625e#diff-47c625e8dc3265ed493265a79b1e823c I think we should change ".. code-block::"  to ".. code:: " so its about linting problem.
 This is a [useful link](https://gitlab.com/pycqa/flake8/commit/9553c8d8ccf54221153f498e28297d9cc74ca12d) Finally I found the solution.  
`E999 SyntaxError: invalid syntax causes flake8 to skip AST tests. Keep mandatory E999 issues in blocks with :flake8-group: Ignore to preserve full testing for the rest of the blocks.`
[link is here](https://pypi.org/project/flake8-rst/) if I add a whitespace after .. code-block:: `flake8-rst` works good but your script `! grep -n '--exclude=*.'{svg,c,cpp,html,js} --exclude-dir=env -RI "\s$" * | awk -F ":" '{print "##vso[task.logissue type=error;sourcepath=" $1 ";linenumber=" $2 ";] Tailing whitespaces found: " $3}'` gives error.

So I will change code-block to .. code::

If I convert it to `.. code::` it won't give `E999` flake8 error and `tailing whitespaces` error.

I test it manually from my local computer. I hope it will work and I think this is a bug.  Thanks! Did you render the html? do you mind copying a screenshot to see how it looks? > Thanks! Did you render the html? do you mind copying a screenshot to see how it looks?

Yes I rendered it on my local machine. 

[image link](https://www.imgpaste.net/image/rGT06)

( *imgur was banned in Turkey. So I uploaded the screenshot to this site.* ) @oktaysabak Thanks for the screenshot! That's looking good, and CI is passing now ;) So merging, thanks again for your contribution! This is my first merge in a big project. Thank you !