Add array of fontScale presets

[kyleshevlin]

Shevy does not intend to solve anyone's font size decisions, but that doesn't mean we can't make some presets to let devs have some good options to start with.

[frytyler]

Hey @kyleshevlin I can hit this for you, I noticed you already provide a set of defaultOptions here so is this intended to provided a set of fontScale's like multiple options to choose from. Is there an example from the scss repo?

[kyleshevlin]

I was considering creating some default typography scales based on tools like the following:

http:https://type-scale.com/
http:https://www.modularscale.com/

Instead of an array, it could be an object with keys that represent scales like 'major-third', 'augmented-fourth', etc, where the value is a font-scale array.

Then, the user can either pass an array or a string to font-scale and Shevy would respond accordingly. We probably want to throw an error if the key doesn't exist.

Those are my thoughts on how I was going to solve it.