As Harald suggests, you are likely better off packaging your HTML as a full-fledged article. The link he provided has information on how to do that. With this approach your HTML winds up being a real article in the DPS 2015 system and can be added to collections, etc. just like any other article.
You can link to any article via name, even if it isn't in your collection. So just make your HTML as a .article file, publish it (but not in any collection), and then create navto links to it wherever you want.
HTMLResources.zip isn't available in DPS 2015. For your situation you don't need it, the actual .article approach will work fine.
But there is a question for me. Is it possible to hide this HTML-article? It shouldn't be displayed in the layout of the collection and it shouldn't be seen if you browse through the pages of the app. It should only appear if you tap on a link .
By the way HTMLResources.zip (like in DPS) doesn't exist in DPS 2015 anymore?