Merge branch 'tools-final2' into docs-mw

Our documentation-related tools are spread out over various directories;
several are buried in the scripts/ dumping ground.  That makes them harder
to discover and harder to maintain.

Recent work has started accumulating our documentation-related tools in
/tools/docs.  This series nearly completes that task, moving most of the
rest of our various utilities there, hopefully fixing up all of the
relevant references in the process.

The one exception is scripts/kernel-doc; that move turned up some other
problems, so I have dropped it until those are ironed out.

At the end, rather than move the old, Perl kernel-doc, I simply removed it.