git: openjdk/jdk-sandbox: classfile-api-dev-branch: Tweak JEP link

[duke]

Changeset: 89c62ba0
Author:    Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
Committer: GitHub <noreply at github.com>
Date:      2022-06-24 08:39:26 +0000
URL:       https://git.openjdk.org/jdk-sandbox/commit/89c62ba037bbf3e71d50974d7e71c39cd6c02bec

Tweak JEP link

! README.md