Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r241710

est(4) man page update to document the exposed sysctl r/o variables
available to the user. Should be applicable to all branches and versions
where est(4) exists.

MFC r241727

Fix minor whitespace issues.

MFC r237245, r237250, r237251, r237273, r237330

Document support for Intel Enhanced Speedstep Tech interface
of cpufreq(4) via a new man page est(4)

Document the two exposed tuneables of est(4).

Numerous cleanups and mdoc updates from reviewers. Thanks to mav, joel,
wblock, hrs, gjb

Document support for Intel Enhanced Speedstep Tech interface
of cpufreq(4) via a new man page est(4)

Document the two exposed tuneables of est(4).

I'd appreciate more reviews of content if possible. I gleaned
the information contained herein from sys/x86/cpufreq/est.c and
the Intel reference documentation

Reviewed by: wblock hrs gjb
MFC after: 2 weeks