Support for YAML config

[fregante]

These are the names/types of config allowed:

xo/lib/constants.js

Lines 118 to 124 in fd8828d

	const CONFIG_FILES = [
	'package.json',
	`.${MODULE_NAME}-config`,
	`.${MODULE_NAME}-config.json`,
	`.${MODULE_NAME}-config.js`,
	`${MODULE_NAME}.config.js`
	];

But both eslint and cosmiconfig natively support YAML files as config:

• https://github.com/davidtheclark/cosmiconfig
• https://eslint.org/docs/user-guide/configuring/configuration-files#using-configuration-files

So it'd be great to see support here too, enabling comments without having to deal with JS files (e.g. #468)

[sindresorhus]

That was an intentional choice. YAML is an awful format. I don't want to encourage use of it. I'd rather support JSON with comments if that's truly needed, but I think it's better to just use JS for config then.

[fregante]

I think it's better to just use JS for config then.

I suppose that could work, hoping that #468 is fixed soon. It was the reason why RG changed the config to JSON in refined-github/refined-github#4002

ESLint also seems to have the same issue with config in ESM packages: eslint/eslint#14137

---

I suppose #428 would also be a solution to this issue 😁