added note to README about the advanced options that are unavailable when using the command line script (https://github.com/jakesgordon/sprite-factory/issues/3)
added note to README about the advanced options that are unavailable when using the command line script (https://github.com/jakesgordon/sprite-factory/issues/3)

jakesgordon/sprite-factory,manaflask/sprite-factory,bastiRe/sprite-factory,bastiRe/sprite-factory,strzibny/sprite-factory,strzibny/sprite-factory,manaflask/sprite-factory,jakesgordon/sprite-factory