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/install/upgrade.md

@@ -0,0 +1,55 @@
+# Upgrade
+
+This article walks you through how to upgrade your Coder server.
+
+<blockquote class="danger">
+  <p>
+  Prior to upgrading a production Coder deployment, take a database snapshot since
+  Coder does not support rollbacks.
+  </p>
+</blockquote>
+
+To upgrade your Coder server, simply reinstall Coder using your original method
+of [install](../install).
+
+## Via install.sh
+
+If you installed Coder using the `install.sh` script, re-run the below command
+on the host:
+
+```shell
+curl -L https://coder.com/install.sh | sh
+```
+
+The script will unpack the new `coder` binary version over the one currently
+installed. Next, you can restart Coder with the following commands (if running
+it as a system service):
+
+```shell
+systemctl daemon-reload
+systemctl restart coder
+```
+
+## Via docker-compose
+
+If you installed using `docker-compose`, run the below command to upgrade the
+Coder container:
+
+```shell
+docker-compose pull coder && docker-compose up -d coder
+```
+
+## Via Kubernetes
+
+See
+[Upgrading Coder via Helm](../install/kubernetes.md#upgrading-coder-via-helm).
+
+## Via Windows
+
+Download the latest Windows installer or binary from
+[GitHub releases](https://github.com/coder/coder/releases/latest), or upgrade
+from Winget.
+
+```pwsh
+winget install Coder.Coder
+```