doc: remove stability warning in v8 module doc

Remove note indicating that the APIs can change at any time. This module
migrated from Experimental to Stable 6 years ago (in io.js 1.4.2).

PR-URL: https://github.com/nodejs/node/pull/35774


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>