Add javadoc-extension in docs-build#1915

ngocnhan-tran1996 wants to merge 1 commit intospring-projects:docs-buildspring-projects/spring-authorization-server:docs-buildfrom

ngocnhan-tran1996:improve-antora-docs-buildngocnhan-tran1996/spring-authorization-server:improve-antora-docs-buildCopy head branch name to clipboard