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/admin/users/headless-auth.md

@@ -0,0 +1,31 @@
+# Headless Authentication
+
+Headless user accounts that cannot use the web UI to log in to Coder. This is
+useful for creating accounts for automated systems, such as CI/CD pipelines or
+for users who only consume Coder via another client/API.
+
+> You must have the User Admin role or above to create headless users.
+
+## Create a headless user
+
+<div class="tabs">
+
+## CLI
+
+```sh
+coder users create \
+  --email="coder-bot@coder.com" \
+  --username="coder-bot" \
+  --login-type="none \
+```
+
+## UI
+
+Navigate to the `Users` > `Create user` in the topbar
+
+![Create a user via the UI](../../images/admin/users/headless-user.png)
+
+</div>
+
+To make API or CLI requests on behalf of the headless user, learn how to
+[generate API tokens on behalf of a user](./sessions-tokens.md#generate-a-long-lived-api-token-on-behalf-of-another-user).