README: add TOC

README.md

@@ -6,6 +6,38 @@ See also:
 - [TODO.md](./TODO.md)
 - [NixOS.md](./NixOS.md)
 
+## Table of Contents
+
+<!-- TOC -->
+* [nix-git](#nix-git)
+  * [Table of Contents](#table-of-contents)
+  * [NixOS installation](#nixos-installation)
+    * [Graphical installation](#graphical-installation)
+  * [Remote installation: disko and nixos-anywhere](#remote-installation-disko-and-nixos-anywhere)
+  * [ARM device: SD image for the Raspberry Pi 3B+](#arm-device-sd-image-for-the-raspberry-pi-3b)
+    * [ISO](#iso)
+    * [Default configuration](#default-configuration)
+    * [Apply modified configuration](#apply-modified-configuration)
+  * [ARM device: Vanilla UEFI boot loader for the Raspberry Pi 3B+](#arm-device-vanilla-uefi-boot-loader-for-the-raspberry-pi-3b)
+  * [Update, build and switch](#update-build-and-switch)
+    * [Update](#update)
+    * [Build and switch: Using Colmena](#build-and-switch-using-colmena)
+    * [Build and switch: Manually](#build-and-switch-manually)
+      * [Option I: Build new config and activate it:](#option-i-build-new-config-and-activate-it)
+      * [Option II: Build new config and activate it during next boot:](#option-ii-build-new-config-and-activate-it-during-next-boot)
+      * [Option III: Build config and view changes:](#option-iii-build-config-and-view-changes)
+  * [niv: Dependency management](#niv-dependency-management)
+    * [Add Home Manager with niv](#add-home-manager-with-niv)
+    * [Add NUR with niv](#add-nur-with-niv)
+  * [Colmena: Deployment and secret management](#colmena-deployment-and-secret-management)
+  * [BTRFS swap file](#btrfs-swap-file)
+  * [LUKS Parameters](#luks-parameters)
+  * [Automount encrypted drive](#automount-encrypted-drive)
+  * [Failed services](#failed-services)
+  * [Garbage collection](#garbage-collection)
+  * [References](#references)
+<!-- TOC -->
+
 ## NixOS installation
 
 ### Graphical installation