Remove annotated string API from HISTORY.md

[nhz2]

The annotated string API was marked as experimental in #55845

This PR updates HISTORY.md to reflect those changes.

[Seelengrab]

I think it would be better to have an explicit Experimental section rather than complete removal. Otherwise people are not going to know that experimental changes are even available for, well, experimenting.

Also, if this is official policy, should it also apply to other experimental things like --trim?

[nhz2]

Discourse may be a better place for announcing experimental changes. There isn't an official policy as far as I can tell.

[Seelengrab]

If there is no official policy, why do these history items in particular need to be removed?

[nhz2]

A new Julia user reading these release notes could reasonably assume that this API is a new stable part of the language. They don't have to be removed, but this part of the release notes needs to be updated to avoid confusion.

[Seelengrab]

That's right, hence my question whether this should apply to --trim too, since that is also considered experimental:

julia/contrib/juliac.jl

Line 2 in 860188f

# NOTE: The interface and location of this script are considered unstable/experimental

It feels odd to me to single out one feature here, purging it from the HISTORY.md. I'm not aware of any case of this happening before.