Attempt to improve/clarify the "Online demo" section of the README
Attempt to improve/clarify the "Online demo" section of the README

Hopefully this will help, now that there's *two* version of the viewer available.

mozilla/pdf.js,showpad/mozilla-pdf.js,Shoobx/pdf.js,showpad/mozilla-pdf.js,Shoobx/pdf.js,timvandermeij/pdf.js,Snuffleupagus/pdf.js,macroplant/pdf.js,nawawi/pdf.js,showpad/mozilla-pdf.js,caremerge/pdf.js,Shoobx/pdf.js,timvandermeij/pdf.js,timvandermeij/pdf.js,macroplant/pdf.js,Snuffleupagus/pdf.js,macroplant/pdf.js,mozilla/pdf.js,xavier114fch/pdf.js,Snuffleupagus/pdf.js,nawawi/pdf.js,caremerge/pdf.js,nawawi/pdf.js,mozilla/pdf.js,xavier114fch/pdf.js