docs: document API

README.md

@@ -14,28 +14,71 @@ automatically.
 
 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, 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.
-
 ## Modules
 
-As with all NixOS configurations, Aether is split into several independent modules that provide different functionality. These are stored in the `modules/` directory.
+As with all good NixOS configurations, Aether is split into *modules* that
+each provide different functionality. These are stored in the `modules/` directory.
 
 ### Module Checklist
 
+- [x] `wireless` - WiFi support
+- [x] `ssh` - SSH configuration
 - [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
 
+## Deployment
+
+Aether is designed to separate individual machine details from the abstract
+specification of the system, allowing for deployment to several different
+types of system. This is handled using *deployments* in the `deploy/` directory.
+
+Currently, I deploy Aether 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. The NixOS code for this can be found in `deploy/rpi5/`.
+
+## External Usage
+
+If you use NixOS and are interested in any of these modules, you can import
+them for your own config!
+
+Add this repository as a flake input:
+
+``` nix
+{
+  inputs.aether.url = "https://git.tokinanpa.dev/toki/aether/archive/main.tar.gz";
+}
+```
+
+Aether modules are then exposed under `nixosModules.<name>` and deployments
+under `nixosModules.deploy-<name>`. You can activate a module by adding it
+to your `imports`:
+
+``` nix
+{
+  imports = with aether.nixosModules; [
+    # Deployment
+    deploy-rpi5
+    # Modules
+    forgejo
+    ssh
+  ];
+
+  # Required by forgejo module
+  aether.domain = "...";
+}
+```
+
+Any number of modules can be activated at once, but activating more than one
+deployment will cause issues, so that should be avoided.
+
+Some modules have options that can be used to configure their effects. If a
+module has options, they can be found in the `options.nix` file inside the
+module directory. More general options used by multiple modules are
+documented in `modules/options.nix`.
+
 [^1]: Adapted from [Book II.1](http://classics.mit.edu/Aristotle/heavens.2.ii.html).