Minor documentation addition
Minor documentation addition

liuruxian/libextobjc,WPDreamMelody/libextobjc,sandyway/libextobjc,goodheart/libextobjc,telly/libextobjc,bboyesc/libextobjc,jiakai-lian/libextobjc,sanojnambiar/libextobjc,kolyuchiy/libextobjc,sunfei/libextobjc,KBvsMJ/libextobjc