docs: update with smartphone

README.md

@@ -32,6 +32,7 @@ See also:
   * [Automount encrypted drive](#automount-encrypted-drive)
   * [List active and failed services](#list-active-and-failed-services)
   * [View system log](#view-system-log)
+  * [Server maintenance with a smartphone](#server-maintenance-with-a-smartphone)
 <!-- TOC -->
 
 ## NixOS installation
@@ -339,3 +340,18 @@ journalctl -p err -b
 # GNOME session logs since last boot. https://help.gnome.org/admin/system-admin-guide/stable/session-debug.html.en
 journalctl _UID="${UID}" -b
 ```
+
+## Server maintenance with a smartphone
+
+While I was on a bike tour I did some config changes to update my NixOS servers using only my smartphone and Nitrokey (GPG smartcard):
+
+- `ome-manager.users.yoda.programs.git.signing.signByDefault = false;`
+- Import `../../modules/git.nix` in `hosts/yodaNas/configuration.nix`
+- Import `./../modules/docker-pushrm.nix` in `hosts/yodaNas/configuration.nix`
+- In `hieve.nix`, set `allowLocalDeployment` to `true` for `yodaNas` and `yodaHedgehog`
+
+This allowed me to connect with my servers via `ssh`, `git clone` this NixOS configuration, build and switch to it with `colmena` and `git commit` and `git push` any changes.
+
+On my smartphone I was using a terminal emulator with `ssh` and GPG smartcard support.
+
+Another approach would have been to run `colmena` directly on the phone.