git: openjdk/jdk-sandbox: classfile-api-dev-branch: readme update

[Adam Sotona]

Changeset: 1023f3d0
Author:    Adam Sotona <asotona at openjdk.org>
Date:      2023-04-11 10:02:50 +0000
URL:       https://git.openjdk.org/jdk-sandbox/commit/1023f3d04554c1d975018b48fddf27116f389817

readme update

! README.md