task #29239886

commit aa5eee355b466cb33f97f79bed9740a472c4ab73 upstream

Important information is missing from user/admin cpuidle documentation
available today, so add a new user/admin document for cpuidle containing
current and comprehensive information to admin-guide and drop the old
.txt documents it is replacing.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Nyjia <yingbao.jia@intel.com>
Signed-off-by: NErwei Deng <erwei@linux.alibaba.com>
Reviewed-by: NArtie Ding <artie.ding@linux.alibaba.com>