Documentation of Inotify::into_event_stream is misleading

[hannobraun]

The documentation for Inotify::event_stream is out of date.

1. It talks about using an internal buffer, but it no longer does.
2. It could use examples showing the various usage scenarios.

The examples should document what kinds of values can be passes as a buffer. See this comment in #124 and this comment in #125 for more information.

[hannobraun]

event_stream is deprecated now, but the documentation of its successor, into_event_stream, still talks about the same internal buffer that doesn't exist.