docs: document modules

README.md

@@ -17,18 +17,25 @@ In short, it's my personal web server.
 ## Deployment
 
 Aether is designed to separate deployment from the logical specification of the
-system, and thus to support any machine that can run NixOS. Currently, it is
-deployed physically to a
+system, and thus to support any machine that can run NixOS.
+
+Currently, I deploy it physically to a
 [Raspberry Pi 5](https://wiki.nixos.org/wiki/NixOS_on_ARM/Raspberry_Pi_5)
 running a [modified UEFI bootloader](https://github.com/worproject/rpi5-uefi)
 to provide Linux support.
 
-## Module Checklist
+## Modules
 
-- [x] `forgejo.nix` - Code forge
-- [ ] `site.nix` - Personal website
-- [ ] `mail.nix` - Mail server
-- [ ] `backup.nix` - Automated backup system
-- [ ] `cachix.nix` - Nix build caching
+As with all NixOS configurations, Aether is split into several independent modules that provide different functionality. These are stored in the `modules/` directory.
+
+### Module Checklist
+
+- [x] `forgejo` - Code forge
+- [x] `acme` - TLS certificates
+- [x] `fail2ban` - IP moderation
+- [ ] `site` - Personal website
+- [ ] `mail` - Mail server
+- [ ] `backup` - Automated backup system
+- [ ] `cachix` - Nix build caching
 
 [^1]: Adapted from [Book II.1](http://classics.mit.edu/Aristotle/heavens.2.ii.html).