Allow showing 1-2 lines "Notes" to the Metronome Player when loading from Library

Allow a song to have a short hint (drums start; everyone starts together, etc) that would show in the player

Hey we already have this suggestion https://suggestions.soundbrenner.com/149 but it was not planned to add something to the Player - although that would make quite a lot of sense too. So I'll keep it up for that

Changed the title from "One or two line hints for song" to "App: Allow showing 1-2 lines "Notes" to the Metronome Player when loading from Library"