docs

[Werner]

The glossary says „Stichnoten“ is in english cue-notes and explains:
„In a separate part notes belonging to another part with the purpose of hinting
when to start playing. Usually printed in a smaller type.“

Unfortunately another meaning is missing. Sometimes there are smaller notes in a
voice as alternative (e.g. for players not able to play as low or as high, the
normal notes are).
(Like ossia, but not in a separate stave!)

So there should be added information, hints and cross-references to snippets 
like

<< { f2 g4 f } \\ { \set fontSize = #-2 e4 d e f } >>

in glossary an NR from ossia AND cue-notes sections!

(see
http://thread.gmane.org/gmane.comp.gnu.lilypond.general/48156/focus=48158
)