Ability to change "VAT" to GST in the invoices totals section under "Total Net Amount"

This will be useful for those who work with customers based in Singapore. They do not refer taxes as VAT, but rather GST. This would benefit any who works with clients in Singapore and keeps up professionalism, accuracy and best practices.

When editing the invoices in PDF Themes, there isn't an option to change the field name of the VAT.