Changed Singapore dollar sign to 'S$'

[taufik-rama]

Hello :wave:

I'm currently using the library, and I think I found a case where a currency symbol is ambiguous.

For Singapore currency sign, I think it can be changed from just $ to S$ (wikipedia), since currently I'm supporting both the USD & SGD currency, and it's kinda confusing when both are displayed

The sign symbol seems to be outside of the scope of the ISO, so I'm guessing it's fine since there doesn't seem to be any standard for it

[varunsrin]

If we're doing this, it should be done consistently across all colliding currencies otherwise it leads to some inconsistent behaviors.

[taufik-rama]

I don't have much to say regarding other currencies, that might take some work/discussion for sure!

To me, I'd like the open-source approach of letting other people that benefit from this library to contribute, since I don't know what's best for other people that uses the currencies might expect

All in all it's not an urgent changes though, since it might be too specific for my usecase. I'm fine with closing this issue