docs: restructure docs (#14421)

Closes #13434 
Supersedes #14182

---------

Co-authored-by: Ethan <39577870+ethanndickson@users.noreply.github.com>
Co-authored-by: Ethan Dickson <ethan@coder.com>
Co-authored-by: Ben Potter <ben@coder.com>
Co-authored-by: Stephen Kirby <58410745+stirby@users.noreply.github.com>
Co-authored-by: Stephen Kirby <me@skirby.dev>
Co-authored-by: EdwardAngert <17991901+EdwardAngert@users.noreply.github.com>
Co-authored-by: Edward Angert <EdwardAngert@users.noreply.github.com>

docs/reference/api/index.md

@@ -0,0 +1,27 @@
+Get started with the Coder API:
+
+## Quickstart
+
+Generate a token on your Coder deployment by visiting:
+
+```shell
+https://coder.example.com/settings/tokens
+```
+
+List your workspaces
+
+```shell
+# CLI
+curl https://coder.example.com/api/v2/workspaces?q=owner:me \
+-H "Coder-Session-Token: <your-token>"
+```
+
+## Use cases
+
+See some common [use cases](../../reference/index.md#use-cases) for the REST API.
+
+## Sections
+
+<children>
+  This page is rendered on https://coder.com/docs/reference/api. Refer to the other documents in the `api/` directory.
+</children>