add a nav section for packages
add a nav section for packages

jakemac53/dartdoc,d2m/dartdoc-2015,astashov/dartdoc,dart-lang/dartdoc,keertip/dartdoc,keertip/dartdoc,srawlins/dartdoc,astashov/dartdoc,srawlins/dartdoc,dart-lang/dartdoc,dart-lang/dartdoc,srawlins/dartdoc,astashov/dartdoc,jakemac53/dartdoc,d2m/dartdoc-2015,jakemac53/dartdoc,d2m/dartdoc-2015,srawlins/dartdoc,keertip/dartdoc,dart-lang/dartdoc,keertip/dartdoc,astashov/dartdoc,jakemac53/dartdoc,d2m/dartdoc-2015