Use consistent return types for available_monitors() (#1207)

* [#1111] Use consistent return types for available_monitors()

Always use `impl Iterator<Item = MonitorHandle>` instead of
`AvailableMonitorsIter`. Fix an example that used the Debug
implementation of `AvailableMonitorsIter`.

* [#1111] Update changelog

* [#1111] Remove AvailableMonitorsIter type completely

* [#1111] Remove doc references to AvailableMonitorsIter

src/event_loop.rs

@@ -11,11 +11,7 @@
 //! [send_event]: ./struct.EventLoopProxy.html#method.send_event
 use std::{error, fmt, ops::Deref, time::Instant};
 
-use crate::{
-    event::Event,
-    monitor::{AvailableMonitorsIter, MonitorHandle},
-    platform_impl,
-};
+use crate::{event::Event, monitor::MonitorHandle, platform_impl};
 
 /// Provides a way to retrieve events from the system and from the windows that were registered to
 /// the events loop.
@@ -150,10 +146,10 @@ impl<T> EventLoop<T> {
     /// Returns the list of all the monitors available on the system.
     #[inline]
     pub fn available_monitors(&self) -> impl Iterator<Item = MonitorHandle> {
-        let data = self.event_loop.available_monitors();
-        AvailableMonitorsIter {
-            data: data.into_iter(),
-        }
+        self.event_loop
+            .available_monitors()
+            .into_iter()
+            .map(|inner| MonitorHandle { inner })
     }
 
     /// Returns the primary monitor of the system.