User, Admin, and Developer guides.

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.

docs/developer-guide.md

@@ -0,0 +1,33 @@
+# Kubernetes Developer Guide
+
+The developer guide is for anyone wanting to either write code which directly accesses the
+kubernetes API, or to contribute directly to the kubernetes project.
+It assumes some familiarity with concepts in the [User Guide](user-guide.md) and the [Cluster Admin
+Guide](cluster-admin-guide.md).
+
+
+## Developing against the Kubernetes API
+
+* API objects are explained at [http://kubernetes.io/third_party/swagger-ui/](http://kubernetes.io/third_party/swagger-ui/).
+
+* **Annotations** ([annotations.md](annotations.md)): are for attaching arbitrary non-identifying metadata to objects.
+  Programs that automate Kubernetes objects may use annotations to store small amounts of their state.
+
+* **API Conventions** ([api-conventions.md](api-conventions.md)):
+  Defining the verbs and resources used in the Kubernetes API.
+
+* **API Client Libraries** ([client-libraries.md](client-libraries.md)):
+  A list of existing client libraries, both supported and user-contributed.
+
+## Writing Plugins
+
+* **Authentication Plugins** ([authentication.md](authentication.md)):
+  The current and planned states of authentication tokens.
+
+* **Authorization Plugins** ([authorization.md](authorization.md)):
+  Authorization applies to all HTTP requests on the main apiserver port.
+  This doc explains the available authorization implementations.
+
+## Contributing to the Kubernetes Project
+
+See this [README](../docs/devel/README.md).