Add support for yamlfix.toml configuration files

[viccie30]

The precedence I've implemented is .yamlfix.toml overrides yamlfix.toml overrides pyproject.toml, but I don't know if that's the wanted order or filenames. I have added a test and changed the documentation to match the changes.

This would close issues #233 and #292.

Checklist

• Add test cases to all the changes you introduce
• Update the documentation for the changes

[coveralls]

Pull Request Test Coverage Report for Build 18305886138

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.004%) to 99.016%

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Totals
Change from base Build 17504881807:	0.004%
Covered Lines:	503
Relevant Lines:	508

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💛 - Coveralls

[lyz-code]

thank you so much for the contribution

[lyz-code]

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