Tooling: suppress header, use filename in caption

The generated index includes a header, but that makes it tricky to include.  

For example, this source:

Renders as folows:

I think that the "AcceptHeaderService : interface" is unnecessary (there would normally be a paragraph here anyway if there was some javadoc for the class).

It would be nice though to use the class as a caption:

[source,java]
.AcceptHeaderService.java
----
public interface  AcceptHeaderService {
   ...
}
----

Extending the idea... 

I think it might be useful to include "API" as a section, but after the top-level paragraph.

In other words, the generated file would be:

The paragraph(s) taken from the javadoc of the class interface.

There might be quite a lot of text here.

= API

[source,java]
.AcceptHeaderService.java
----
public interface AcceptHeaderService {
  ...
}
----

These generated files will then be included quite nicely into the refguide pages.