[PATCH] cpufreq: documentation for 'ondemand' and 'conservative'

Added a more verbose entry for the 'ondemend' governor and an entry for the
'conservative' governor to the documentation.

Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>