API manual: fixes and additions

doc/manual.md

@@ -22,18 +22,24 @@ and an optional [association list](https://lilypond.org/doc/v2.24/Documentation/
 which can be used to pass options.
 
 ```lilypond
+\include "lilygabc.ily"
+
 \score { \gabc "(c4) A(ghg)men(fg)" }
 
-% using the optional argument
 \score {
-  \gabc #'((produce . voice)
-           (voice-id . "my_voice_1"))
-        "(c4) A(ghg)men(fg)"
-  \new Lyrics \lyricsto "my_voice_1" { La -- la }
+  <<
+    % using the optional argument
+    \gabc #'((produce . voice)
+             (voice-id . "my_voice_1"))
+      "(c4) A(ghg)men(fg)"
+    \new Lyrics \lyricsto "my_voice_1" { La -- la }
+  >>
 }
 ```
 
-Supported options (the key is always a symbol):
+### Options
+
+(The key is always a symbol.)
 
 - `parse-as` - value `gly` (symbol) makes the input be handled
   as [gly][gly] *music line(s)* rather than gabc.
@@ -50,6 +56,8 @@ Supported options (the key is always a symbol):
   which is useful mainly for attaching additional lyrics
   to the same voice in LilyPond code.
 
+### Functions
+
 The functions are a matrix combining
 input format (gabc / gly),
 notation style (modern / square notation, which is called Vaticana in the LilyPond world)
@@ -76,6 +84,17 @@ as separate functions, allowing parsed gabc data to be used repeatedly
 to produce output of different kinds or
 to be transformed before producing some sort of output.
 
+```lilypond
+\include "gregorian.ly"
+\include "lilygabc.ily"
+
+parsed = \lilygabc-parse-gabc "(c4) A(ghg)men(fg)"
+
+\score { \lilygabc-vaticana-music \parsed }
+\score { \lilygabc-modern-music \parsed }
+\score { \lilygabc-modern-notes \parsed }
+```
+
 ### Parsing input
 
 Both functions accept input as string and return parsed