RFR 8167227: Simplify the JDK 9 API-specification overview page (docs only)

[John Rose]

On Jun 18, 2017, at 3:47 AM, mark.reinhold at oracle.com wrote:
> 
> Current output, for reference:
> http://download.java.net/java/jdk9/docs/api/overview-summary.html <http://download.java.net/java/jdk9/docs/api/overview-summary.html>

Yes, the language changes are good.  (From a non-legal English major POV.)

I also reviewed the makefile mechanics; those look good AFAICT.

— John