Introduce one-time binding in style-guide?

The normal approach for data-binding in angular is by using `{{vm.foobar}}` this introduce a two-way binded variable and angular initiates a $watcher. After Angular 1.3 there is a way to reduce this $watcher and in case where only one-time binding is needed `{{::vm.foobar}}` syntax can be used. 

This will help reduce number of $watchers and increase performance. 
