Adds docs/compute_resources.md with user-oriented
explanation of compute resources.
Reveals detail gradually and includes examples
and troubleshooting. Examples are tested.
Moves design-focused docs/resources.md to docs/design/resources.md.
Updates links to that.
Put discussion of how to access the API ahead of discussion about
how to access other services on the cluster.
More clearly distinguish the different kinds of proxies.
Explain pros and cons of different approaches better.
Remove cluster-admin-oriented documentation from user guide.
More links.
First pass at organizing our docs for three separate audiences:
User, Cluster Admin, and developer. Wrote a top-level guide
for each one, by selecting parts of the old docs/README.md.
The new docs/README.md mostly points to these 3 guides.
