Improvment prelude for emacs 26.1

[RastaDill]

Hello. I tryed install prelude-mode in emacs 26.1 and it's not working the out of box.
Many packages in MELPA required emcas 27.1.
I read "Pinning packages" from documentation, but i don't understand how correct enabled via variables.

What i do:

1. copy prelude-pinned-packages.el in emacs.d/ (root folder) because prelude-packages.el automatically load this file if have.
2. disabled melpa reposilory because after added pinned packages the stable melpa not have priority over melpa
3. refresh packages before install use-packages, otherwise package not installed
4. changed vertico by default on ivy for emacs < 27.1 because vertico in stable melpa required 27.1
5. (*) added SSH_AUTH_SOCK in exec-path-from-shell for situation if somebody can't use ssh for magit (disabled by default)

As a result the prelude not working in emacs 25.1 the out of box. Many packages minimum requre 27.1 or 26.1.
To maintain backward compatibility, I see quelpa.

If my solution will be right, I updated changelog and documentation

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by checking the relevant checkboxes):

• The commits are consistent with our contribution guidelines
• You've updated the changelog (if adding/changing user-visible functionality)
• You've updated the user manual (if adding/changing user-visible functionality like modules, commands, configuration options, etc)

Thanks!

[RastaDill]

I tryed use helm but faced with problem. Pckage wfname don't installed - error message: unavailable. For solved it i added nongnu repository http://elpa.nongnu.org/ in prelude-pinned-packages.el

[bbatsov]

I've normally aimed to support the last 3 major Emacs releases, so now that Emacs 29 is out I guess it'd be best to target Emacs 27 directly. (especially given how many packages don't support Emacs 26 anymore)

[RastaDill]

I understand, so I guess this PR may be closed. But I have one question. This problem generation of impossible the package.el to freeze extension to Emacs version and not provided rollback package.
Thanks for your article "Package Management in Emacs: The Good, the Bad and the Ugly". It has been more than 10 years, but nothing changes. Now I see nobody set tags in the Emacs add-on community. All your constraints in the article I guess are solved the straight.el. Why don't Prelude use it?