[expo-docs] Update docs to reflect that Expo.fonts.loadAsync actually returns a p…
[expo-docs] Update docs to reflect that Expo.fonts.loadAsync actually returns a p…

…romise.

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Closes expo/expo-docs#264

exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent