doc: add futures-concurrency as dev dependency for testing

tokio/Cargo.toml

@@ -133,6 +133,7 @@ tokio-stream = { version = "0.1", path = "../tokio-stream" }
 futures = { version = "0.3.0", features = ["async-await"] }
 mockall = "0.11.1"
 async-stream = "0.3"
+futures-concurrency = "7.6.0"
 
 [target.'cfg(not(target_family = "wasm"))'.dev-dependencies]
 socket2 = "0.5.5"

tokio/src/macros/select.rs

@@ -523,7 +523,7 @@ macro_rules! doc {
         /// - [`futures_lite::future::or`](https://docs.rs/futures-lite/latest/futures_lite/future/fn.or.html)
         /// - [`futures_lite::future::race`](https://docs.rs/futures-lite/latest/futures_lite/future/fn.race.html)
         ///
-        /// ```ignore
+        /// ```
         /// use futures_concurrency::future::Race;
         ///
         /// #[tokio::main]