fix: deprecated nativeStyleToProp to nativestyleMapping

[Jin-Byun]

I was trying to get SymbolView from expo-symbols to work with styled.
The v5/api/styled show example of using nativeStyleToProp, when v5 uses nativeStyleMapping instead.

// from doc instruction
const StyledSymbolView = styled(SymbolView, {
    className: {
        target: "style",
        nativeStyleToProp: {
            tintColor: "style.color",
            weight: "style.fontWeight",
            size: "style.fontSize",
        },
    },
});

// what actually works
const StyledSymbolView = styled(SymbolView, {
    className: {
        target: "style",
        nativeStyleMapping: {
            color: "tintColor",
            fontWeight: "weight",
            fontSize: "size",
        },
    },
});

Currently, the only valid type for nativeStyleMapping (if declared) is Record<string,string>, like [styleSheetKey]: componentPropsKey,
This is a minimal change in documentation (just changing the code example), but I think it would be nice if this page could be structured like the api/withNativeWind page, with options describing target, nativeStyleMapping, etc in the future.

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