Make supported ember versions bold in the readme
Make supported ember versions bold in the readme

Dremora/ember-power-select,cibernox/ember-power-select,esbanarango/ember-power-select,chrisgame/ember-power-select,Dremora/ember-power-select,esbanarango/ember-power-select,cibernox/ember-power-select,cibernox/ember-power-select,esbanarango/ember-power-select,cibernox/ember-power-select,chrisgame/ember-power-select