docs(trace): add documentation to trace module and new features to feature list

Document `trace` and add new features to the documentation feature list.
Modify `package.metadata.docs.rs` in `Cargo.toml` to include `tracing`
to list of `features` and `--cfg hyper_unstable_tracing` to the list of
`rustdoc-args`.

Author: RamziA961

Cargo.toml

@@ -91,8 +91,8 @@ tracing = ["dep:tracing"]
 nightly = []
 
 [package.metadata.docs.rs]
-features = ["ffi", "full"]
-rustdoc-args = ["--cfg", "docsrs", "--cfg", "hyper_unstable_ffi"]
+features = ["ffi", "full", "tracing"]
+rustdoc-args = ["--cfg", "docsrs", "--cfg", "hyper_unstable_ffi", "--cfg", "hyper_unstable_tracing"]
 
 [package.metadata.playground]
 features = ["full"]

src/lib.rs

@@ -67,8 +67,11 @@ pub use crate::error::{Error, Result};
 
 #[macro_use]
 mod cfg;
+
 #[macro_use]
+#[cfg_attr(docsrs, doc(all(feature = "tracing"), hyper_unstable_tracing))]
 mod trace;
+
 #[macro_use]
 mod common;
 pub mod body;

src/trace.rs

@@ -1,5 +1,34 @@
+// For completeness, wrappers around all of tracing's public macros are provided, even if they are
+// not used at the present time.
 #![allow(unused_macros)]
 
+//! Internal Tracing macro module
+//!
+//! The [`trace`][crate::trace] module is an internal module that contains wrapper macros encapsulating
+//! [`tracing`][tracing]'s macros. These macros allow for conditional expansion of
+//! [`tracing`][tracing] macros during compilation when the `tracing` feature is enabled, or trimming
+//! them when the feature is disabled, all in a concise manner.
+//!
+//! The macros from the [`trace`][crate::trace] module are declared by default and can be used throughout the
+//! crate. However, as the contents of these macros are conditionally compiled, they are effectively trimmed
+//! during inline expansion when the `tracing` feature is disabled.
+//!
+//! # Unstable
+//!
+//! The [`tracing`][tracing] module is currenty **unstable**, hence the existence of this module. As a
+//! result, hyper's [`tracing`][tracing] logs are only accessibe if `--cfg hyper_unstable_tracing` is
+//! passed to `rustc` when compiling. The easiest way to do that is through setting the `RUSTFLAGS`
+//! enviornment variable.
+//!
+//! # Building
+//!  
+//! Enabling [`trace`][crate::trace] logs, can be done with the following `cargo` command, as of
+//! version `1.64.0`:
+//!
+//! ```notrust
+//! RUSTFLAGS="--cfg hyper_unstable_tracing" cargo rustc --features client,http1,http2,tracing --crate-type cdylib
+//! ```
+
 macro_rules! debug {
     ($($arg:tt)+) => {
         #[cfg(feature = "tracing")]