doc: revise stability section of values doc

Make the section a bit shorter and comply with minor elements of
Microsoft Style Guide.

PR-URL: https://github.com/nodejs/node/pull/35242


Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>