Set up "vanity url" for internal Carbon site

[shinytoyrobots]

The internal Carbon site suffers from poor discoverability. The redesign should address this problem from the ground up, by consolidating the internal and external sites.

But in the meantime, we should have an easily memorable / promotable url to send internal users to. This will be especially important when the new IBM Design site launches and we push significant internal traffic to Carbon.

Possible contenders:
ibm.biz/carbon
ibm.biz/carbon-internal
ibm.com/carbon-internal
???

(from @claycrenshaw)

[shinytoyrobots]

Couple of comments

1. We will probably need to hold off or have something generic that doesn't use the Carbon name (as we seem to be transitioning towards the idea of "IBM Design System" or something similar.
2. docs: updated content to reference IBM Design Language design-system-website#355 probably avoids the need to push any significant internal-only traffic (now that the Duo name has gone away, there's no real need for that content to be internal only).

[alisonjoseph]

will live here http://w3.ibm.com/design/product