docs: Include Spell Flags in Magic Documentation

[RobbieNeko]

Purpose of change

I noticed that the magic flags still weren't in the docs evidently, so I put them in here myself. Thought they'd be helpful to be in the docs, rather than making people look through the magic.h file.

Describe the solution

Copies the list of valid spell flags from magic.h to the documentation with appropriate formatting

Describe alternatives you've considered

Continue to be mildly annoyed at the lack of spell flags in the documentation.

Testing

Attempted to match the formatting of the rest of the file as best I can. It's docs, so it at least won't break the game even if I did somehow screw up that royally.

Additional context

^-^

[autofix-ci]

The Autofix app has found code style violation and automatically formatted this Pull Request.

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1. Format your code locally, then commit it.
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