Adding an SCR section to the docs

[john-science]

What is the change? Why is it being made?

Here I add a new process to ARMI. Instead of just a random "release notes" section, every ARMI PR will come with an SCR. This is part of the on-going quality work in ARMI.

Notes:

1. This PR will be the first PR merged after the release of ARMI 0.5.1.
2. To reduce merge conflicts, I have not moved over the 0.5.rst release notes yet. I will do that before I merge this.)

SCR Information

Change Type: docs

One-Sentence Description: ARMI now has an automated "SCR" section, instead of a manual "Release Notes" section that has to be tweaked in code.

One-line Impact on Requirements: NA

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Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify any new/changed code.
• The code style follows good practices.
• The documentation is still up-to-date in the doc folder.
• The dependencies are still up-to-date in pyproject.toml.

[john-science]

Here is a little proof this works in HTML:

And you can see proof this works in PDF here: https://github.com/terrapower/armi/actions/runs/13725317705?pr=2090

[opotowsky]

Looks good! I know you have to wait to merge, but you have the green check for when you need it.

Update: haha, I submitted this review before checking CI. I'm assuming you're just troubleshooting the token.