Core reference and Libraries reference entries share the same template

Because there's a single template to build all of the reference pages, the Library reference pages have the wrong left-nav option selected (Reference and not Libraries). Also, they can't have a custom message at the top of the page about the Javadoc. I think this requires digging into java-generate and rebuilding the Java classes.

In addition, the non-core Libraries from the Processing Foundation (Video and Sound) can't have a separate header message. They link to the Libraries Javadoc, but the code isn't there. Thinking about this more, we could probably build those Javadocs and add them while the rest are built.

首先检查共享的参考页面模板以及 issue 中提到的 java-generate 入口点，然后跟踪 Java 类是如何重新构建的。完成的标准是：Library 页面在左侧导航中选择 Libraries，支持自定义 Javadoc 消息，并且 Video 和 Sound 页面按预期处理其 Javadoc 链接或生成的 Javadocs。