docs(pool): add module level docs for pools (#248)

Author: seanmonstar

Cargo.toml

@@ -77,7 +77,7 @@ full = [
 
 client = ["hyper/client", "tokio/net", "dep:tracing", "dep:futures-channel", "dep:tower-service"]
 client-legacy = ["client", "dep:socket2", "tokio/sync", "dep:libc", "dep:futures-util"]
-client-pool = ["dep:futures-util", "dep:tower-layer"]
+client-pool = ["client", "dep:futures-util", "dep:tower-layer"]
 client-proxy = ["client", "dep:base64", "dep:ipnet", "dep:percent-encoding"]
 client-proxy-system = ["dep:system-configuration", "dep:windows-registry"]
 

src/client/pool/mod.rs

@@ -1,4 +1,8 @@
 //! Composable pool services
+//!
+//! This module contains various concepts of a connection pool separated into
+//! their own concerns. This allows for users to compose the layers, along with
+//! any other layers, when constructing custom connection pools.
 
 pub mod cache;
 pub mod map;