Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- Add $FreeBSD$
- Refer to the README files in the subdirs.

Clean up some of the tortured english in this file.

README reads:
This directory tree contains tools used for the maintenance of FreeBSD.
There are no Makefile structure, but possibly Makefiles in some of the
subdirs.
Nothing show be installed from here and into the running system.
This directory should contain only subdirs and this file.