skpkg: add news file and update file-level comments

[zmx27]

No description provided.

[zmx27]

@sbillinge ready for review. This should be the end of the migration process, and migration is ready to be merged into main! I've checked over all the files and made sure they're up to standards.
Here are the results of running precommit:

check yaml...............................................................Passed
fix end of files.........................................................Passed
trim trailing whitespace.................................................Passed
check for case conflicts.................................................Passed
check for merge conflicts................................................Passed
check toml...............................................................Passed
check for added large files..............................................Passed
black....................................................................Passed
flake8...................................................................Passed
isort....................................................................Passed
nbstripout...........................................(no files to check)Skipped
Prevent Commit to Main Branch............................................Passed
codespell................................................................Passed
prettier.................................................................Passed
docformatter.............................................................Passed

And here are the results of running pytest on the minimal tests that I wrote:

================================= test session starts =================================
platform darwin -- Python 3.13.7, pytest-8.4.2, pluggy-1.6.0
rootdir: /Users/zhimingxu/BillingeGroup/diffpy.srxconfutils/diffpy.srxconfutils
configfile: pyproject.toml
plugins: env-1.1.5, cov-7.0.0
collected 3 items

tests/test_tools.py ..                                                          [ 66%]
tests/test_version.py .                                                         [100%]

================================== 3 passed in 9.35s ==================================

[sbillinge]

nice! Thanks. One last thing. Please can you check that all the github workflows are consistent with those in the diffpy.pdfgetx project rather than scikit package. I checked on the tests-on-pr and it is, but please double check all the other workflows.

I will merge this. I will merge migration into main when you confirm the workflows are all ok.

Please then make an issue to update the build script in the main xpdfsuite repo to remove the migration branch from this project, and make that PR if possible.

Thanks so much @zmx27 very exciting.