add a note explaining sharing options
add a note explaining sharing options

cr3ative/StoryMapJS,1modm/StoryMapJS,BenHeubl/StoryMapJS,makinacorpus/StoryMapJS,cr3ative/StoryMapJS,cr3ative/StoryMapJS,wangjun/StoryMapJS,wangjun/StoryMapJS,wangjun/StoryMapJS,1modm/StoryMapJS,jorol/StoryMapJS,makinacorpus/StoryMapJS,BenHeubl/StoryMapJS,wangjun/StoryMapJS,makinacorpus/StoryMapJS,BenHeubl/StoryMapJS,1modm/StoryMapJS,jorol/StoryMapJS,jorol/StoryMapJS,1modm/StoryMapJS,BenHeubl/StoryMapJS,jorol/StoryMapJS,cr3ative/StoryMapJS