\spacingTweaks disappears from manuals

[Knute Snortum]

I noticed that \spacingTweaks disappeared from the manuals in v2.23.
Looking through the commits, I find this by Jean:

https://gitlab.com/lilypond/lilypond/-/commit/fcf9604b0322310a26818a3a3b3f820ffb329a60

It basically says that \spacingTweaks was unsed and undocumented, so
he removed it.  This is fine, except it *was* documented in v2.22
through v2.20 at least.  My questions are:

* should there be a mention on the Changes manual page that it's gone?

* should there be a rule in python/convertrules.py at least putting a
"deprecated" in front of it, or issuing some sort of warning?

This is not a big deal, I was just surprised that \spacingTweaks
disappeared without a mention.  I'm open to all opinions, including
just leaving it as it is.

--
Knute Snortum