[docs][glossary] Add page that lists all standardized k8s terms (#5657)

* Add comprehensive glossary page

Additional Authors:
* Andrew Chen <chenopis@users.noreply.github.com>
* Steve Perry <steveperry-53@users.noreply.github.com>

* incorporate Tim's feedback

* address zach's comments

* address more comments

* add additional crosslinking

* Add platform developer, tweak formatting for disambiguation cases or multiparagraph definitions.

_data/glossary/kubectl.yaml

@@ -0,0 +1,9 @@
+id: kubectl
+name: Kubectl
+tags:
+- tool
+- fundamental
+short-description: |
+  A command line tool for communicating with a [Kubernetes API](#term-kubernetes-api) server.
+long-description: |
+  You can use kubectl to create, inspect, update, and delete Kubernetes objects.