#5404 Doc: 2.4.2, fix harmonic-mixed example

[Federico Bruni]

https://lists.gnu.org/archive/html/bug-lilypond/2018-08/msg00042.html

Hi Bug Squad,
See:
http://lilypond.org/doc/v2.18/Documentation/notation/guitar.html#indicating-harmonics-and-dampened-notes
And:
http://lilypond.org/doc/v2.19/Documentation/notation/guitar.html#indicating-harmonics-and-dampened-notes

1. I don't understand the reason to put the NoteHead defs at a Staff level.
2. Maybe a whole note is not the best example to show the 'harmonic-mixed
   result.

How about changing this snieppet:

~~~~~
\relative c' {
\clef "treble_8"
\override Staff.NoteHead.style = #'harmonic-mixed
d^\markup { \italic { \fontsize #-2 { "harm. 12" }}} <g b="">1
}</g>

To:

\relative c' {
\clef "treble_8"
\override NoteHead.style = #'harmonic-mixed
d8^\markup { \italic { \fontsize #-2 { "harm. 12" }}} <g b="">4
}
~~~~</g>

[Federico Bruni]

Later Harm suggested:

Agreed. Also, why not delete some of the superfluous brackets in the
markup? Only keeping the surrounding ones for better viewable
structure. I.e.

\markup { \italic \fontsize #-2 "harm. 12" }

[Anonymous]

Doc: 2.4.2, fix harmonic-mixed example

Issue 5404

Remove 'Staff', simplify braces
and change note value to give a
clearer example.

http://codereview.appspot.com/344070043

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

change d to d' as per Thomas' suggestion.

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdown for 1st September

[Anonymous]

Patch counted down - please push.

[Anonymous]

Doc: 2.4.2, fix harmonic-mixed example
author  James Lowe <pkx166h@runbox.com> 
    Sun, 26 Aug 2018 11:58:43 +0100 (11:58 +0100)
committer   James Lowe <pkx166h@runbox.com> 
    Sun, 2 Sep 2018 13:59:20 +0100 (13:59 +0100)
commit  a52b774568830c4f63087aff1ccb3b0885cb7a18