Add docs for the `#[variant(enum)]` attribute.
@@ -709,10 +709,23 @@ godot_test!(
/// - `Struct { a, b, c }` is represented as a `Dictionary` (`{ "a": a, "b": b, "c": c }`)
/// - `Unit` is represented as an empty `Dictionary` (`{}`)
/// - `Enum::Variant(a, b, c)` is represented as an externally tagged `Dictionary`
-/// (`{ "Variant": [a, b, c] }`)
+/// (`{ "Variant": [a, b, c] }`), unless another representation is specified with
+/// `#[variant(enum)]` (see below).
///
/// Behavior of the derive macros can be customized using attributes:
///
+/// ### Item attributes
+///
+/// - `#[variant(enum = "str")]`
+///
+/// Only applicable to field-less enums. Variants of types annotated with this attribute
+/// are represented as stringified values of their names, i.e. `"Variant"` for `Enum::Variant`.
+///
+/// - `#[variant(enum = "repr")]`
+///
+/// Only applicable to field-less enums with a explicit primitive `#[repr]` type. Variants of
+/// types annotated with this attribute are represented as their primitive integral values.
+///
/// ### Field attributes
///
/// - `#[variant(to_variant_with = "path::to::func")]`
