doc: remove incorrect, redundant IR info-dir-section.
The code that creates the file internals.texi, which is found in ./scm/documentation-generate.scm and ./scm/documentation-lib.scm, inserts the following texinfo code near the beginning of the file:
INFO-DIR-SECTION LilyPond
START-INFO-DIR-ENTRY
* GNU LilyPond Internals Reference: (internals). LilyPond Internals Reference.
END-INFO-DIR-ENTRY
This texinfo code is incorrect as the reference '(internals)' points to a non-existent file; it should read '(lilypond-internals)'. It is also redundant as the main info dir section for LilyPond already contains a menu item that points to the correct file. As far as I can tell, this incorrect code affects only the internals.info, file so removing it will not impact any other document.
I suggest removing this code. The requested merge also removes the incorrect function texi-file-head as it will be no longer called by any code.
Edited by John Wheeler