Mismatch between implementation and documentation for fixed32/fixed64 conversion

[guillaume-rochette-oxb]

Hi @0x26res,
I have noticed a mismatch between the documentation regarding the mapping of the native types, where it is stated that fixed32 and fixed64 will be converted to int32 and int64 respectively.
However, I believe that the implementation behaves differently, and effectively fixed32 and fixed64 will be converted to uint32 and uint64 respectively.
I suggest that we update the documentation so that it matches the implementation, what do you think?
Best regards,
Guillaume

[0x26res]

Indeed, thanks for fixing. #123