docs(ngBindHtml): explain that angular-sanitize.js is needed to depend on ngSanitize
docs(ngBindHtml): explain that angular-sanitize.js is needed to depend on ngSanitize

Added comment. You need to include angular-sanitize.js otherwise you cant use ngSanitize!

Closes #9400

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js