Added how to upgrade channel

README.md

@@ -7,11 +7,7 @@ My NixOS configuration repository
 2. Reboot into NixOS
 3. Edit `/etc/nixos/configuration.nix` with sudoedit
     - Change hostname
-    - Enable flakes. Add the following lines:
-```
-# Enable flakes
- nix.settings.experimental-features = [ "nix-command" "flakes" ];
-```
+    - Enable flakes by adding the line `nix.settings.experimental-features = [ "nix-command" "flakes" ];`
     - Install tmux, neovim, git by adding them to `environment.systemPackages = with pkgs; [`
 4. Apply changes: `sudo nixos-rebuild switch` and reboot
 5. Clone NixOS config repository to /home/$USER/nixos:
@@ -37,6 +33,17 @@ Then, perform nixos rebuild:
 sudo nixos-rebuild switch --flake ~/nixos/#<host>
 ```
 
+## Upgrading to a new NixOS channel
+List the current channels:
+```
+sudo nix-channel --list
+```
+Change the channel `nixos`:
+```
+sudo nix-channel --add https://nixos.org/channels/nixos-<rel>
+```
+Then, perform an update like above.
+
 ## Garbage Collection
 List all generations:
 ```