elm multibuttonentry: Updated document. I know this sucks this widget is wrongly designed.
elm multibuttonentry: Updated document. I know this sucks this widget is wrongly designed.

Signed-off-by: Daniel Juyung Seo <juyung.seo@samsung.com>

SVN revision: 68873

rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary