docs: update credits documentation to reflect MC base currency implementation

src/controllers/docs.rs

@@ -162,7 +162,7 @@ impl DocsController {
         render_template(&tmpl, "docs/services.html", &ctx)
     }
 
-    /// USD Credits documentation page
+    /// Mycelium Credits documentation page
     pub async fn credits(tmpl: web::Data<Tera>, session: Session) -> Result<impl Responder> {
         let mut ctx = crate::models::builders::ContextBuilder::new()
             .active_page("docs")