tokio: remove documentation stating `Receiver` is clone-able. (#2037)

* tokio: remove documentation stating `Receiver` is clone-able.

The documentation for `broadcast` stated that both `Sender` and
`Receiver` are clonable. This isn't the case: `Receiver`s cannot be
cloned (and shouldn't be cloned).

In addition, mention that `Receiver` is `Sync`, and mention that both
`Receiver` and `Sender` are `Send`.

Fixes: #2032

* Clarify that Sender and Receiver are only Send and Sync if T is Send or Sync.

1 files changed, 3 insertions, 2 deletions

diff --git a/tokio/src/sync/broadcast.rs b/tokio/src/sync/broadcast.rs
index ce803724..f915da6c 100644
--- a/tokio/src/sync/broadcast.rs
+++ b/tokio/src/sync/broadcast.rs
@@ -2,8 +2,9 @@
 //! all consumers.
 //!
 //! A [`Sender`] is used to broadcast values to **all** connected [`Receiver`]
-//! values. Both [`Sender`] and [`Receiver`] handles are clone-able, allowing
-//! concurrent send and receive actions. Additionally, [`Sender`] is `Sync`.
+//! values. [`Sender`] handles are clone-able, allowing concurrent send and
+//! receive actions. [`Sender`] and [`Receiver`] are both `Send` and `Sync` as
+//! long as `T` is also `Send` or `Sync` respectively.
 //!
 //! When a value is sent, **all** [`Receiver`] handles are notified and will
 //! receive the value. The value is stored once inside the channel and cloned on