feat: add mastodon module

README.md

@@ -31,14 +31,28 @@ 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`.
 
-### Module Checklist
+### Modules
+
+Modules listed here may be unimplemented or unfinished.
+
+#### Basic
 
 - [x] `basic` - Basic Internet support
 - [x] `ssh` - SSH support
-- [ ] `site` - Static site hosting
 - [x] `fail2ban` - IP moderation
+
+#### Public Sites
+
+- [ ] `site` - Static site hosting
 - [x] `forgejo` - Code forge
+
+#### Social
+
+- [x] `mastodon` - Mastodon server instance
 - [ ] `mail` - Mail server
+
+#### Storage
+
 - [ ] `cachix` - Nix build caching
 - [ ] `backup` - Automated backup system