Fix swapped reference numbering in get_bsrn docstring

[aman-coder03]

• Closes Correct referencing in pvlib.iotools.get_bsrn #2679
• I am familiar with the contributing guidelines
• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

The order of references was correct, but labels [3] and [4] were interchanged.

[cwhanse]

thanks @aman-coder03 !

[ramaroesilva]

@aman-coder03 @cwhanse ups...

[cwhanse]

Derp. [2] and [4] are reversed. Thank you @ramaroesilva

[aman-coder03]

oops!😅
i will make it rightt no issues, shall I? @cwhanse

[aman-coder03]

```
References
----------
.. [1] `World Radiation Monitoring Center - Baseline Surface Radiation
    Network (BSRN)
    <https://bsrn.awi.de/>`_
.. [2] `Update of the Technical Plan for BSRN Data Management, 2013,
   Global Climate Observing System (GCOS) GCOS-174.
   <https://bsrn.awi.de/fileadmin/user_upload/bsrn.awi.de/Publications/gcos-174.pdf>`
.. [3] `BSRN Data Retrieval via FTP
   <https://bsrn.awi.de/data/data-retrieval-via-ftp/>`
.. [4] `BSRN Data Release Guidelines
   <https://bsrn.awi.de/data/conditions-of-data-release/>`

[cwhanse]

@ramaroesilva I looked again. I think the reference order is now correct in iotools.get_bsrn and in iotools.read_bsrn. Where did you get that screenshot?

[cwhanse]

It is somewhat confusing that all three BSRN functions cite the same 4 references, but in a different order that conforms to each function's docstring.

[aman-coder03]

i fixed the order like it was in the screenshot in the #2681

[ramaroesilva]

@cwhanse, sorry my bad. this printscreen was actually from read_bsrn doc so there may be a separate problem there.

to me, get_bsrn doc looks the same as originally. does the PR automatically show up in the online doc or only when a new version is released? thought it could be a cache issue, but I checked also in anonymous mode and in a different browser and still got the two issues.

[kandersolar]

@ramaroesilva be sure to check https://pvlib-python.readthedocs.io/en/latest/ instead of https://pvlib-python.readthedocs.io/en/stable/. stable only updates when we make a new release. latest reflects the latest commit on the main branch.

[ramaroesilva]

Thanks @kandersolar! Always learning new things :-)

@aman-coder03, looks great now!