This adds documentation on authenticating with API tokens and writing

custom API policies.
The authentication docs now cover how to log in with either API tokens

or a username/password. Some of the existing docs here are also fleshed

out to create better examples.
The new API token policy docs cover the structure of policies, the

various sections of the policy, how they affect access, and some tips.

This will complement the UI for editing tokens, which is currently in

development.
All API resource pages now also contain the policy IDs for use in the

policies.

Built the docs and read through them. Didn't see any errors from these pages.
Checked the resource docs and saw the payload IDs.