Make it easier to add all routes

[sholladay]

From the usage instructions of hapi-docs:

If you want a route to appear in the documentation, you have to set tags: [api] for this specific route.

I find this really annoying, for a few reasons:

1. I have to go in and add tags : ['api'] to every single API route individually, of which I have a large number. Adding these tags is tedious.
2. We use an /api prefix in the URL, as many people do, to delineate which routes are APIs. The tag needlessly duplicates this information.
3. I am forced to add an api tag to any route that I want to document, even if the route is not an API. Thus, the tag is actually nonsensical.

What I really want is to document all routes by default, the way that lout does. Or at least make it easy to document all routes under the /api URL prefix at once, without adding tags to each individual route.