Added javadoc to `[Labeled,MenuItem].mnemonicParsing` property, taken from the `MnemonicInfo` internal class.
A CSR may not be needed since it's a mere clarification and not an API change, but I am not sure. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - explain mnemonic Changes: https://git.openjdk.org/jfx/pull/2287/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2287&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8390898 Stats: 55 lines in 2 files changed: 41 ins; 2 del; 12 mod Patch: https://git.openjdk.org/jfx/pull/2287.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/2287/head:pull/2287 PR: https://git.openjdk.org/jfx/pull/2287
