updated index.restdown
updated index.restdown

added more (clearer) instructions for creating HTTPS server

`fs.readFileSync` to read the files as described on https://nodejs.org/api/https.html

myroid/node-restify,mcavage/node-restify,joyent/node-restify,jameswomack/node-restify,sean3z/node-restify,kusor/node-restify,trentm/node-restify,restify/node-restify,restify/node-restify,gergelyke/node-restify,BryanDonovan/node-restify,myroid/node-restify,hekike/node-restify