docs(readme): add IE 11 Support notes (#648)
docs(readme): add IE 11 Support notes (#648)

added section on ie11 support and how to make bootstrap-vue work with this browser.
bootstrap-vue/bootstrap-vue,tmorehouse/bootstrap-vue,SirLamer/bootstrap-vue,sschadwick/bootstrap-vue,sschadwick/bootstrap-vue,mosinve/bootstrap-vue,tmorehouse/bootstrap-vue,mosinve/bootstrap-vue,sschadwick/bootstrap-vue,bootstrap-vue/bootstrap-vue,SirLamer/bootstrap-vue