RFR: 8325093: Update CONTRIBUTING.md for build jdk version

Fri Feb 2 13:40:06 UTC 2024

On Thu, 1 Feb 2024 06:36:51 GMT, Ao Qi <aoqi at openjdk.org> wrote:

> [JDK-8297068](https://bugs.openjdk.org/browse/JDK-8297068) updated boot JDK to 19.0.1 from 18.0.2, and [JDK-8321434](https://bugs.openjdk.org/browse/JDK-8321434) updated boot JDK to 21.0.1. `CONTRIBUTING.md` should be updated correspondingly.

Looks good. Thanks.

-------------

Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1357#pullrequestreview-1859268381