docs: Document that vpath and json macros are feature-gated (#3615)

axum-extra/src/response/erased_json.rs

@@ -130,6 +130,7 @@ impl IntoResponse for ErasedJson {
 /// ```
 /// let response = axum_extra::json!(["trailing",]);
 /// ```
+#[cfg_attr(docsrs, doc(cfg(feature = "erased-json")))]
 #[macro_export]
 macro_rules! json {
     ($($t:tt)*) => {

axum-extra/src/routing/mod.rs

@@ -68,6 +68,7 @@ pub const fn __private_validate_static_path(path: &'static str) -> &'static str
 /// ```
 ///
 /// This macro is available only on rust versions 1.80 and above.
+#[cfg_attr(docsrs, doc(cfg(feature = "routing")))]
 #[rustversion::since(1.80)]
 #[macro_export]
 macro_rules! vpath {