Improve readme and docs with debouncers

[0xpr03]

Just a todo to add more explanation to notify's front readme and lib.rs.

Would be nice to directly give users more information about notify vs notify-debouncer-mini vs -full, that they exist and which one to choose. Searching for notify on crates.io also doesn't show more than notify itself, so this would definitely help.

The current readme is too detailed and diverges into FSevents, which isn't exactly beginner friendly.

Also add a link to the list of known issues from notify into the debouncers docs. Probably need to see which ones don't apply for debouncers.