docs: remove redundant words in comment (#7224)

Author: jimmycathy

tokio-stream/src/pending.rs

@@ -17,7 +17,7 @@ unsafe impl<T> Sync for Pending<T> {}
 ///
 /// The returned stream is never ready. Attempting to call
 /// [`next()`](crate::StreamExt::next) will never complete. Use
-/// [`stream::empty()`](super::empty()) to obtain a stream that is is
+/// [`stream::empty()`](super::empty()) to obtain a stream that is
 /// immediately empty but returns no values.
 ///
 /// # Examples

tokio/src/runtime/scheduler/inject/rt_multi_thread.rs

@@ -60,7 +60,7 @@ impl<T: 'static> Shared<T> {
 
     /// Inserts several tasks that have been linked together into the queue.
     ///
-    /// The provided head and tail may be be the same task. In this case, a
+    /// The provided head and tail may be the same task. In this case, a
     /// single task is inserted.
     #[inline]
     unsafe fn push_batch_inner<L>(

tokio/src/util/metric_atomics.rs

@@ -4,7 +4,7 @@ cfg_64bit_metrics! {
     use std::sync::atomic::AtomicU64;
 }
 
-/// `AtomicU64` that is is a no-op on platforms without 64-bit atomics
+/// `AtomicU64` that is a no-op on platforms without 64-bit atomics
 ///
 /// When used on platforms without 64-bit atomics, writes to this are no-ops.
 /// The `load` method is only defined when 64-bit atomics are available.