docs: Updated after stablizing runtime metrics

Author: ranger-ross

README.md

@@ -146,7 +146,7 @@ loop {
 
 ## Getting Started With Runtime Metrics
 
-This unstable functionality requires `tokio_unstable`, and the  `rt` crate
+Not all runtime metrics are stable. Using unstable metrics requires `tokio_unstable`, and the  `rt` crate
 feature. To enable `tokio_unstable`, the `--cfg` `tokio_unstable` must be passed
 to `rustc` when compiling. You can do this by setting the `RUSTFLAGS`
 environment variable before compiling your application; e.g.:

src/lib.rs

@@ -56,11 +56,11 @@
 //! ```
 
 #![cfg_attr(
-    all(tokio_unstable, feature = "rt"),
+    feature = "rt",
     doc = r##"
-### Monitoring runtime metrics (unstable)
+### Monitoring runtime metrics
 [Monitor][RuntimeMonitor] key [metrics][RuntimeMetrics] of a tokio runtime.
-**This functionality requires `tokio_unstable` and the crate feature `rt`.**
+**This functionality requires crate feature `rt` and some metrics require `tokio_unstable`.**
 
 In the below example, a [`RuntimeMonitor`] is [constructed][RuntimeMonitor::new] and
 three tasks are spawned and awaited; meanwhile, a fourth task prints [metrics][RuntimeMetrics]
@@ -104,7 +104,7 @@ async fn do_work() {
 }
 ```
 
-### Monitoring and publishing runtime metrics (unstable)
+### Monitoring and publishing runtime metrics
 
 If the `metrics-rs-integration` feature is additionally enabled, this crate allows
 publishing runtime metrics externally via [metrics-rs](metrics) exporters.

src/runtime.rs

@@ -1007,6 +1007,7 @@ pub struct RuntimeMetrics {
     /// let mut next_interval = || intervals.next().unwrap();
     ///
     /// let interval = next_interval(); // end of interval 1
+    /// # #[cfg(tokio_unstable)]
     /// assert_eq!(interval.num_remote_schedules, 0);
     ///
     /// // spawn a system thread outside of the runtime
@@ -1020,6 +1021,7 @@ pub struct RuntimeMetrics {
     /// drop(runtime);
     ///
     /// let interval = next_interval(); // end of interval 2
+    /// # #[cfg(tokio_unstable)]
     /// assert_eq!(interval.num_remote_schedules, 2);
     /// # }
     /// ```