v1.5.9
docs(guide): tweaks to the index and external resources guides
fix(input[range]): make support for `input[range]` opt-in
docs(guide/concepts): improve wording
fix(jenkins): Fix the format for passing parameters to Grunt tasks
feat(ngdocs): support popover, foldouts and foldover annotations
docs(tutorial/step_04): fix syntactic error (add missing 'a')