Deleted disambiguate_symbol for USD

[igor-alexandrov]

USD should not have disambiguate_symbol and prices in USD should always be formatted like $10,000, the documentation confirms this: https://github.com/RubyMoney/money/blob/main/lib/money/money/formatter.rb#L181.

Currently, Money.new(100, 'USD').format(disambiguate: true) prints US$1.00, which is wrong and confusing.

[s-mage]

but this is correct. There are other currencies that use this symbol, e.g. Mexican Peso. If you're in Mexico you'd think $ means peso, not US dollar. If you're outside of Mexico and US, you, strictly speaking, can't tell.

[igor-alexandrov]

If this is correct, then the documentation should be updated because it says the opposite.

At the same time, if you really need to disambiguate USD, you can always override the default config with Money::Currency.inherit, so I think, the proposed change is correct.