Re-export watches::Watches at crate root.

[zachs18]

If watches::Watches is not exported publicly, then rustdoc does not show it's documentation, leading to broken doc links in Inotify::watches. (it is a pub item in a private module, so by default it can be used but not named)

See: Inotify::watches: the return type does not have an intra-doc link, and the intra-doc links to Watches::add and Watches::remove lead to 404 pages.

[hannobraun]

Thank you, @zachs18, looks good!