docs: Sync README.md with crate docs

Closes #212

Signed-off-by: John Nunley <[email protected]>

README.md

@@ -19,11 +19,15 @@ Supported platforms:
 - [poll](https://en.wikipedia.org/wiki/Poll_(Unix)): VxWorks, Fuchsia, HermitOS, other Unix systems
 - [IOCP](https://learn.microsoft.com/en-us/windows/win32/fileio/i-o-completion-ports): Windows, Wine (version 7.13+)
 
-Polling is done in oneshot mode, which means interest in I/O events needs to be reset after
-an event is delivered if we're interested in the next event of the same kind.
+By default, polling is done in oneshot mode, which means interest in I/O events needs to
+be re-enabled after an event is delivered if we're interested in the next event of the same
+kind. However, level and edge triggered modes are also available for certain operating
+systems. See the documentation of the [`PollMode`] type for more information.
 
 Only one thread can be waiting for I/O events at a time.
 
+[`PollMode`]: https://docs.rs/polling/latest/polling/enum.PollMode.html
+
 ## Examples
 
 ```rust,no_run