extension proposal

First draft

Mostly a conversation piece here, but I've sat on this for too long.

Fixes #74

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

ext/README.md

@@ -0,0 +1,49 @@
+# Extensions
+
+The basis of the Extension API is described in a document which should be emulated for all extensions.
+
+## Table of Contents
+
+<!-- toc -->
+* [Table](#table)
+* [Name](#name)
+* [Filename](#filename)
+* [Detail](#detail)
+* [Prior Art](#prior-art)
+<!-- /toc -->
+
+## Table
+
+_notice_: All new `./ext/ext-$name.md` docs MUST be added to this table.
+
+| `$name` (and definition) | Summary |
+|:--:|:--:|
+| [0](./ext-0.md) | Extensions discovering extensions on registry server |
+|  |  |
+
+
+## Name
+
+Extension names MUST be unique.
+Names SHOULD include a version.
+
+Each extension's endpoints will be nested below its name.
+
+```HTTP
+    GET /v2/ext/0/...
+```
+
+## Filename
+
+XXX
+
+## Detail
+
+XXX acceptable error codes
+
+## Prior Art
+
+When considering the proposal structure for these extensions, the following processes were considered:
+
+* [Python PEP](https://www.python.org/dev/peps/)
+* [Kubernetes KEP](https://github.com/kubernetes/enhancements/tree/master/keps)

ext/ext-0.md

@@ -0,0 +1,14 @@
+# ext-0 -- Index of Distribution Extensions
+
+## Table of Contents
+
+<!-- toc -->
+* [Summary](#summary)
+* [Reference Explanation](#reference-explanation)
+<!-- /toc -->
+
+## Summary
+
+This base extension is to return the array of names of the extensions.
+
+## Reference Explanation