Update all nroff manpages for JDK 16 release

The man pages in src/$module/man/*.1 is generated from the (unfortunately still) closed markdown sources.

These needs to be updated for JDK 16. During this updating, a typo in the GPL header is also fixed (which caused Oracle's internal header verification tool to complain) -- a double space had been collapsed into a single space.

There is a certain possibility that man page content can still change for JDK 16. If that is the case, the export needs to be re-done. (In contrast to prior exports, we now have a standard way of doing this, so it's trivial to update.)