git: openjdk/jdk-sandbox: classfile-api-dev-branch: fixed docs building

[Adam Sotona]

Changeset: 89d520c8
Author:    Adam Sotona <asotona at openjdk.org>
Date:      2022-12-19 11:13:00 +0000
URL:       https://git.openjdk.org/jdk-sandbox/commit/89d520c87f08d068e4e95fa6cb86d005b91d4d7f

fixed docs building

! make/Docs.gmk