Fix broken GuildChannel collector functionality (#1446)

Currently, `GuildChannel::await_reply` and other collector methods try to await from a "guild" that matches the `GuildChannel`'s ID. This would have functioned normally had default channels not been discontinued (which shared the same ID as the guild), but since they were, the behaviour only works in very old guilds. Furthermore, logic dictates that, since the collector methods are on a `GuildChannel`, they should work by awaiting on the specific channel, but they do not. As such, the collectors are broken. This commit fixes them to work based on the guild channel they're called on instead. 

This commit also fixes an example for `Channel::guild()` where `GuildChannel::name` should be the `GuildChannel` name, not the guild name as the example suggests.

src/model/channel/guild_channel.rs

@@ -1100,44 +1100,44 @@ impl GuildChannel {
         }
     }
 
-    /// Returns a future that will await one message by this guild.
+    /// Returns a future that will await one message by this guild channel.
     #[cfg(feature = "collector")]
     #[cfg_attr(docsrs, doc(cfg(feature = "collector")))]
     pub fn await_reply<'a>(
         &self,
         shard_messenger: &'a impl AsRef<ShardMessenger>,
     ) -> CollectReply<'a> {
-        CollectReply::new(shard_messenger).guild_id(self.id.0)
+        CollectReply::new(shard_messenger).channel_id(self.id.0)
     }
 
-    /// Returns a stream builder which can be awaited to obtain a stream of messages sent by this guild.
+    /// Returns a stream builder which can be awaited to obtain a stream of messages sent by this guild channel.
     #[cfg(feature = "collector")]
     #[cfg_attr(docsrs, doc(cfg(feature = "collector")))]
     pub fn await_replies<'a>(
         &self,
         shard_messenger: &'a impl AsRef<ShardMessenger>,
     ) -> MessageCollectorBuilder<'a> {
-        MessageCollectorBuilder::new(shard_messenger).guild_id(self.id.0)
+        MessageCollectorBuilder::new(shard_messenger).channel_id(self.id.0)
     }
 
-    /// Await a single reaction by this guild.
+    /// Await a single reaction by this guild channel.
     #[cfg(feature = "collector")]
     #[cfg_attr(docsrs, doc(cfg(feature = "collector")))]
     pub fn await_reaction<'a>(
         &self,
         shard_messenger: &'a impl AsRef<ShardMessenger>,
     ) -> CollectReaction<'a> {
-        CollectReaction::new(shard_messenger).guild_id(self.id.0)
+        CollectReaction::new(shard_messenger).channel_id(self.id.0)
     }
 
-    /// Returns a stream builder which can be awaited to obtain a stream of reactions sent by this guild.
+    /// Returns a stream builder which can be awaited to obtain a stream of reactions sent by this guild channel.
     #[cfg(feature = "collector")]
     #[cfg_attr(docsrs, doc(cfg(feature = "collector")))]
     pub fn await_reactions<'a>(
         &self,
         shard_messenger: &'a impl AsRef<ShardMessenger>,
     ) -> ReactionCollectorBuilder<'a> {
-        ReactionCollectorBuilder::new(shard_messenger).guild_id(self.id.0)
+        ReactionCollectorBuilder::new(shard_messenger).channel_id(self.id.0)
     }
 
     /// Creates a webhook with only a name.

src/model/channel/mod.rs

@@ -83,10 +83,10 @@ impl Channel {
     /// #   let channel = ChannelId(0).to_channel_cached(&cache).await.unwrap();
     /// #
     /// match channel.guild() {
-    ///     Some(guild) => {
-    ///         println!("It's a guild named {}!", guild.name);
+    ///     Some(guild_channel) => {
+    ///         println!("It's a guild channel named {}!", guild_channel.name);
     ///     },
-    ///     None => { println!("It's not a guild!"); },
+    ///     None => { println!("It's not in a guild!"); },
     /// }
     /// # }
     /// ```