Add initial resources.md for discussion

The first draft of a Kubernetes resource model.
This is future, so not a huge deal for now, but I don't like this.  It conflates different ideas, and it makes it practically impossible to know how to parse a resource typename.  is "foo.com/a/b" a type named "a/b" or a type named "a" with an subdivision of "b".  We could change the syntax, but I don't know that it is better.

Simply asserting that the value of each key has a type which depends on the key seems sufficient.  DiskSpace then has a type of map[string]int.