[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/reference.yml

@@ -2,6 +2,7 @@ bigheader: "Reference Documentation"
 abstract: "Design docs, concept definitions, and references for APIs and CLIs."
 toc:
 - docs/reference/index.md
+- docs/reference/glossary.md
 
 - title: Using the API
   section:
@@ -108,5 +109,3 @@ toc:
   - title: Kubernetes Issue Tracker on GitHub
     path: https://github.com/kubernetes/kubernetes/issues/
   - docs/reference/security.md
-
-