Merge #904

904: Improve docs of channel creation functions r=taiki-e a=yjhn

Add note that the channel is multi-producer multi-consumer to the functions' docs. Also point to the parent module docs since they contain a lot of info on how to use the channel. These changes make functions' docs more self-contained (previously one needed to know to look at the module docs to discover this info).

Co-authored-by: yjhn <andrius.puksta@gmail.com>

crossbeam-channel/src/channel.rs

@@ -16,10 +16,12 @@ use crate::flavors;
 use crate::select::{Operation, SelectHandle, Token};
 use crate::utils;
 
-/// Creates a channel of unbounded capacity.
+/// Creates a multi-producer multi-consumer channel of unbounded capacity.
 ///
 /// This channel has a growable buffer that can hold any number of messages at a time.
 ///
+/// For more info on how to use the channel see [module level documentation](index.html).
+///
 /// # Examples
 ///
 /// ```
@@ -54,13 +56,15 @@ pub fn unbounded<T>() -> (Sender<T>, Receiver<T>) {
     (s, r)
 }
 
-/// Creates a channel of bounded capacity.
+/// Creates a multi-producer multi-consumer channel of bounded capacity.
 ///
 /// This channel has a buffer that can hold at most `cap` messages at a time.
 ///
 /// A special case is zero-capacity channel, which cannot hold any messages. Instead, send and
 /// receive operations must appear at the same time in order to pair up and pass the message over.
 ///
+/// For more info on how to use the channel see [module level documentation](index.html).
+///
 /// # Examples
 ///
 /// A channel of capacity 1: