Reference ToC refactor (#3427)

* Reference ToC refactor

* Move Federation into Reference

* Fix ToC, add deprecation notice

* Fix Reference ToC

* tweak ToC

* Move content into Reference

* touch up kubectl

* fix ToC syntax error

* remove resources-reference docs

* change kubectl section name

* adjust page titles

* create Command-Line Tools section

* Move Federation API out to top level

* remove extensions/v1beta1 definitions

* rewrite Kubernetes API in Concepts in a later PR

* Add jbeda to Kubernetes API Overview page for reviews.

* incorporate feedback

* remove /docs/federation

* move around copy

* cleanup reference landing page

* update reference landing page

docs/concepts/overview/kubernetes-api.md

@@ -1,13 +1,9 @@
 ---
 assignees:
-- bgrant0607
-- erictune
-- lavalamp
+- chenopis
 title: The Kubernetes API
 ---
 
-Primary system and API concepts are documented in the [User guide](/docs/user-guide/).
-
 Overall API conventions are described in the [API conventions doc](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/docs/devel/api-conventions.md).
 
 API endpoints, resource types and samples are described in [API Reference](/docs/reference).