README: Update link description for example app
README: Update link description for example app

The Wiki page has been updated and the example is an Rails 4 and not 3
app now.

Sorcery/sorcery,Sorcery/sorcery,rubenmoya/sorcery,Borzik/sorcery,Borzik/sorcery,NoamB/sorcery,wasabia/bnbtripSorcery,athix/sorcery,wasabia/bnbtripSorcery,Sology/sorcery,Sorcery/sorcery,athix/sorcery,jshum/sorcery,Sology/sorcery,rubenmoya/sorcery,NoamB/sorcery,athix/sorcery,jshum/sorcery