[DOC] Add reference for ember-routing-named-substates.
Merge pull request #3682 from rjackson/features_update

[DOC] Add reference for ember-routing-named-substates.
remove registerFactory doc reference (its all just register now)
Remove unused local var from link_to test
Merge pull request #3710 from balinterdi/remove-unused-snippet-from-link-to-test

Remove unused local var from link_to test