fix link to contributing guidelines
fix link to contributing guidelines

lependu/ember-cli-mirage,mixonic/ember-cli-mirage,cs3b/ember-cli-mirage,makepanic/ember-cli-mirage,cs3b/ember-cli-mirage,jherdman/ember-cli-mirage,cibernox/ember-cli-mirage,unchartedcode/ember-cli-mirage,unchartedcode/ember-cli-mirage,mixonic/ember-cli-mirage,samselikoff/ember-cli-mirage,cibernox/ember-cli-mirage,jherdman/ember-cli-mirage,lependu/ember-cli-mirage,jherdman/ember-cli-mirage,makepanic/ember-cli-mirage,samselikoff/ember-cli-mirage,samselikoff/ember-cli-mirage,unchartedcode/ember-cli-mirage,jherdman/ember-cli-mirage,samselikoff/ember-cli-mirage,unchartedcode/ember-cli-mirage