Update scss/at-mixin-pattern

[Schascha]

Hello,

stylelint-config-sass-guidelines/index.js

Line 85 in ffa15c4

"scss/at-mixin-pattern": "^[a-z]+([a-z0-9-]+[a-z0-9]+)?$",

maybe prefer this regex:

"scss/at-mixin-pattern": "^[a-z]+(-?[a-z0-9]+)+$"

With that way mixins like h1() are possible and we can prevent mixins with multiple - like foo--bar().

Thanks

[kerryj89]

I feel like with the popularity of BEM maybe double hyphens shouldn't be prevented by default ^[a-z][0-9]?(-{0,2}[a-z0-9]+)*$, but I guess the pattern starts to look too opinionated.

Agreed that the pattern should be updated; funny enough I ran into the same issue with my math variables $x1, $x2, etc. #191

[bjankord]

I'm open to updating this.

[bjankord]

Thinking about this, I don't feel strongly about enforcing a strict regex for mixins. Planning to remove the scss/at-mixin-pattern rule in the next major (v10) release and then people can decide however they want to write their mixins.