Update package path in docs

[dwightjack]

I updated the docs with the correct inclusion path (See ShiftbrainStd/polyrhythm-typography#9).

It looks like the namespace is not used when using the $module parameter in functions like meta.get-function:

@use "sass:meta";
@use "@shiftbrainstd/harmonic-modular-scale";

// works
meta.get-function("get-sizes", $module: "harmonic-modular-scale")

// doesn't work
meta.get-function("get-sizes", $module: "@shiftbrainstd/harmonic-modular-scale")

[dwightjack]

@yuheiy please review

[yuheiy]

LGTM!