Add default_url option to Quick Start example
Add default_url option to Quick Start example

It took me a lot of digging to figure out how to add the
`:default_url` option, but it seems a common option that many
people will need to modify. Putting it anywhere in the README
will help those who just cmd-F on the page, like me.
zurb/paperclip,crowdtap/paperclip,tylerwillingham/paperclip,justanshulsharma/paperclip,Leadformance/paperclip,soramugi/paperclip,Cohealo/paperclip,victorngkp/paperclip,sopheak-se/paperclip,medcat/paperclip,mehulkar/paperclip,alexandrz/paperclip,ScotterC/paperclip,degica/paperclip,zurb/paperclip,sopheak-se/paperclip,InesCARodrigues/paperclip,cmaion/paperclip,carnivalmobile/paperclip,mehulkar/paperclip,victorngkp/paperclip,Sporky023/paperclip,keathley/paperclip,greatbody/paperclip,raow/paperclip,Leadformance/paperclip,onursarikaya/paperclip,pcorliss/paperclip,mrb/paperclip,bdewater/paperclip,agcantarelli/paperclip,greatbody/paperclip,medcat/paperclip,mdkalish/paperclip,soramugi/paperclip,frankpinto/paperclip,crowdtap/paperclip,cmaion/paperclip,carnivalmobile/paperclip,ScotterC/paperclip,maintux/paperclip,degica/paperclip,howaboutwe/paperclip,dgynn/paperclip,tylerwillingham/paperclip,raow/paperclip,betesh/paperclip,joshisa/paperclip,freeslugs/paperclip,aditya01933/paperclip,dgynn/paperclip,rpbaptist/paperclip,freeslugs/paperclip,maintux/paperclip,keathley/paperclip,aditya01933/paperclip,frankpinto/paperclip,felipemathies/paperclip,mrb/paperclip,agcantarelli/paperclip,Sporky023/paperclip,pandamako/paperclip,tiegz/paperclip,mrgilman/paperclip,Cohealo/paperclip,bdewater/paperclip,mdkalish/paperclip,pandamako/paperclip,betesh/paperclip,justanshulsharma/paperclip,joshisa/paperclip,felipemathies/paperclip,alexandrz/paperclip,manorie/paperclip,danielwanja/paperclip,gfvcastro/paperclip,tiegz/paperclip,InesCARodrigues/paperclip,mrgilman/paperclip,onursarikaya/paperclip,gfvcastro/paperclip,manorie/paperclip,rpbaptist/paperclip,sideci-sample/sideci-sample-paperclip