Putting finger substitution in the LilyPond manual

[Knute Snortum]

In this thread (1) we discussed how to notate the piano technique of
holding down one note and changing fingers without releasing the note.
Wikipedia calls this "substitution." (2)  I would like to put a
section in the manual that explains how to notate this.  It seems to
be a fairly common thing in piano music and yet there's no mention of
it that I can find.

I think a quick explanation could go in the Fingering section (3) or
the Keyboard Snippets section (4).  Wikipedia states that this
technique is used by violin players too but I don't know if it is
notated the same way or not.  The text would be something like:

*** begin manual text

Sometimes the keyboardist will want to hold down a key with one finger
then change fingers without lifting the key up.  This is called
substitution and it can be notated several ways.

With a dash between the numbers:

[snippet showing a dash between fingering numbers]

With a tie over or under the numbers:

[snippet showing the \undertie and \overtie techniques]

*** end manual text

Any thoughts on this?

1. https://lists.gnu.org/archive/html/lilypond-user/2021-10/msg00290.html
2. https://en.wikipedia.org/wiki/Finger_substitution
3. 
https://lilypond.org/doc/v2.22/Documentation/learning/within_002dstaff-objects#fingering
4. https://lilypond.org/doc/v2.22/Documentation/snippets/keyboards
--
Knute Snortum