hi there
what part of Note 8 don't you understand ?
it pretty clearly states what dropout voltage it
but just in case you didn't,
say you have a linear regulator IC .... eg a 7805. and its dropout voltage is 2V
that means to get a reliable 5V out you must have at least 7V input, else it wont be able to maintain regulation
different chips have different dropout ratings some as low as 1V ( maybe a little less) others up to around 2.5V
Dave