Added some top level use case info to help with keywords for SEO.

[MicahGale]

Pull Request Checklist for MontePy

Description

This adds some keywords that I learned a user was searching for and barely was able to find MontePy with this search. This tries to add some keywords by using some "use cases" to top level documentation. This will hopefully add useful keywords that SEO will like, without engaging in keyword packing that is penalized, by being natural and actually helpful. Yes this violates my views on the words "card" and "decks". However, I have learned: this is what some users search, and if we want to be helpful, we need to meet the users halfway.

Fixes #754

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General Checklist

• I have performed a self-review of my own code.
• The code follows the standards outlined in the development documentation.
• I have formatted my code with black version 25.
• I have added tests that prove my fix is effective or that my feature works (if applicable).

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Documentation Checklist

• I have documented all added classes and methods.
• For infrastructure updates, I have updated the developer's guide.
• For significant new features, I have added a section to the getting started guide.

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First-Time Contributor Checklist

• If this is your first contribution, add yourself to pyproject.toml if you wish to do so.

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Additional Notes for Reviewers

Ensure that:

• The submitted code is consistent with the merge checklist outlined here.
• The PR covers all relevant aspects according to the development guidelines.
• 100% coverage of the patch is achieved, or justification for a variance is given.

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📚 Documentation preview 📚: https://montepy--775.org.readthedocs.build/en/775/

[tjlaboss]

LGTM

We should also consider (not necessarily as part of this PR) how to improve visibility on Pypi. We're only No. 17 by Relevance, behind some search results which are far less relevant or mature.

[MicahGale]

Agreed. Though how PyPI search works is such a black box it's hard to optimize for.