Incorrect payment type-related input and return types

[Poitrin]

Summary
Documentation has some incorrect input and return types.

Expected documentation

1. shop.enabled_payment_types should return an array of strings (see examples, where enabled_payment_types is used in a loop)
2. For payment_type_svg_tag, syntax should be string | payment_type_svg_tag

Actual documentation

1. shop.enabled_payment_types returns string
2. For payment_type_svg_tag, syntax is type | payment_type_svg_tag