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

[Adam Sotona]

Changeset: 8c18d9be
Author:    Adam Sotona <asotona at openjdk.org>
Date:      2022-07-04 15:42:06 +0000
URL:       https://git.openjdk.org/jdk-sandbox/commit/8c18d9bec318f0ea72c8025bd1270120eda0fc00

fixed docs build

! make/Docs.gmk