improve docs on arbor for file:// ; close #368
improve docs on arbor for file:// ; close #368

soomin-maeng/cytoscape.js,KonstantinShemyak/cytoscape.js,soomin-maeng/cytoscape.js,rlugojr/cytoscape.js,rlugojr/cytoscape.js,KonstantinShemyak/cytoscape.js