Export NUT-06 supported settings field (#764)

* Export NUT-06 supported settings field

* Fix doc test

crates/cashu/src/nuts/nut06.rs

@@ -446,7 +446,8 @@ impl Nuts {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Hash, Serialize, Deserialize)]
 #[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub struct SupportedSettings {
-    supported: bool,
+    /// Setting supported
+    pub supported: bool,
 }
 
 /// Contact Info