change to update format

README.md

@@ -2,4 +2,34 @@ Installs the bare necessities to turn a newly minted Arch Linux server into some
 
 ```
 wget -qO- https://gitea.young.computer/david/MiniServer/raw/branch/main/install.sh | bash
-```
+```
+
+## Keep your server up to date
+
+```
+update
+```
+
+This pulls the latest MiniServer into `~/.local/share/MiniServer`, then runs each step in `updates.d/` in order: the Arch keyring and system packages (plus any packages newly added to `packages.conf`), AUR packages, pm2, sibling projects, cache cleanup, and a reboot check. If a step fails, the others still run and the failed ones are listed at the end.
+
+## Refresh
+
+```
+refresh
+```
+
+Re-runs `install.sh` to pick up anything new in the installer (services, config). Run `update` afterwards.
+
+## Sibling projects
+
+A sibling project is another git repository that builds on MiniServer. To install one:
+
+```
+sibling
+```
+
+It asks for the repository's git URL, clones it into `~/.local/share/siblings/`, and runs the project's `install.sh` (if it has one). After that, every `update` pulls each sibling and runs its `update.sh` (if it has one).
+
+Use `sibling list` to see what's installed and `sibling remove {name}` to uninstall one.
+
+To make your own repository work as a sibling project, see [skills/sibling-project-format.md](skills/sibling-project-format.md).