Add __private_docs feature to axum-extra

Similar to the one in axum.

axum-extra/CHANGELOG.md

@@ -10,11 +10,13 @@ and this project adheres to [Semantic Versioning].
 - **breaking:** Remove unused `async-stream` feature, which was accidentally
   introduced as an implicit feature through an optional dependency which was no
   longer being used ([#3145])
-- **change:** Make the `status` function of rejections a `const` function, such
+- **fixed:** Fix a broken link in the documentation of `ErasedJson` ([#3186])
+- **changed:** Make the `status` function of rejections a `const` function, such
   as `FormRejection`, `QueryRejection` and `MultipartRejection` ([#3168])
 
 [#3145]: https://github.com/tokio-rs/axum/pull/3145
 [#3168]: https://github.com/tokio-rs/axum/pull/3168
+[#3186]: https://github.com/tokio-rs/axum/pull/3186
 
 # 0.10.0
 

axum-extra/Cargo.toml

@@ -41,6 +41,12 @@ tracing = ["axum-core/tracing", "axum/tracing"]
 typed-header = ["dep:headers"]
 typed-routing = ["dep:axum-macros", "dep:percent-encoding", "dep:serde_html_form", "dep:form_urlencoded"]
 
+# Enabled by docs.rs because it uses all-features
+__private_docs = [
+    # Required for the ErasedJson docs to be able to link to axum::Json
+    "axum/json",
+]
+
 [dependencies]
 axum = { path = "../axum", version = "0.8.0", default-features = false, features = ["original-uri"] }
 axum-core = { path = "../axum-core", version = "0.5.0" }