Fixing cpu-hotplug documentation as follows:

 - moving confusing asterisk on additional_cpus descrition
 - fixing some typos
 - unifying indentation for source code and command line example
Signed-off-by: NSatoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>