This allows for the build to fail if a reference isn't found.

This happens because we have the section kind enabled (needed for examples).

This causes `p` tags which is invalid HTML.

No more Ruby dependency and most important more than 10 times less build time (at least on Windows)!

* Change state field to select
* Include "Choose..." placeholder for select
* Change validated select to .custom-select

There's no reason for us to wait here.

Some of the snippets need to be updated later.

As of npm 5.0.0, installed modules are added as a dependency by default, so the --save option is no longer needed. The other save options still exist and are listed in the documentation for npm install.

`aria-haspopup` use requires the use of an ARIA `menu`, `listbox`, `tree`, `grid` or `dialog` (see https://www.w3.org/TR/wai-aria-1.1/#aria-haspopup)

in our use (as generic disclosure widgets), it's incorrect and sets up the wrong assumption/behavior from assistive technologies.

in future, we likely want to change our dropdowns to essentially be like a `dialog` - move focus to it when opened, possibly make it modal so focus is maintained inside it and the rest of the page
is hidden/inert.

but for now, removing the incorrect attribute is probably the quickest, most immediate fix.