Fixes#9344.
Depends on #9821.
Update Secrets documentation to explain how secrets can be
created/used manually, or automatically with service accounts.
Greatly expanded service account documentation.
Added a service account admin guide.
Lots of cross-references.
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.
Updated descriptions and added headers and into statements
Edited the redirect requests section and clarified steps in example
Replaced GCE with Google Compute Engine
Added two statements about the required forward slashes and inserted a '/' into each example.
Per issue 7502, replaced all instances of “v1beta1/proxy” with
“v1beta3/proxy/namespaces/default” and “v1beta1/redirect” with
“v1beta3/redirect/namespaces/default”. Also removed all trailing ‘/‘
forward slashes.
Removed trailing whitespace that caused sync error
Removed whitespace after “for the Kubernetes master followed by
`/api/v1beta3/proxy/namespaces/default/services/myservice/alpha/beta/gam
ma`. “
