Web fonts will not be loaded if fallbacks: false is set

[astrochemx]

Is it expected that web fonts will not be loaded if fallbacks: false is set and webfonts is not set?
If so, I think this should be mentioned in the documentation.
If appropriate, I could make a PR for this later, when I have time.

Ref:

slidev/packages/parser/src/config.ts

Lines 147 to 151 in d9d89c0

	const webfonts = fonts.webfonts
	? fonts.webfonts
	: fallbacks
	? uniq([...sans, ...serif, ...mono, ...custom])
	: []