fix typo in im_message_protocol
fix typo in im_message_protocol

raoxudong/jpush-docs,raoxudong/jpush-docs,Aoyunyun/jpush-docs,jpush/jpush-docs,Aoyunyun/jpush-docs,raoxudong/jpush-docs,jpush/jpush-docs,xiongtiancheng/jpush-docs,xiongtiancheng/jpush-docs,xiongtiancheng/jpush-docs,jpush/jpush-docs,Aoyunyun/jpush-docs,xiongtiancheng/jpush-docs,raoxudong/jpush-docs,jpush/jpush-docs,Aoyunyun/jpush-docs