update README

README.md

@@ -72,13 +72,13 @@ nix --extra-experimental-features nix-command store diff-closures /run/current-s
 Depending on if there are large kernel changes, either switch to it directly or wait until next boot:
 
 ```shell
-# TODO: This is not persistent (after reboot).
 sudo ./result/bin/switch-to-configuration switch
 # or
-# TODO: This does not work. There is no new boot menu entry :/
 sudo ./result/bin/switch-to-configuration boot
 ```
 
+Note: The Perl script executed by both above commands _should_ create a new bootloader menu entry and mark it as default. However, if I remember correctly, the menu entry was once missing and the configuration change thus not permanent. This might need further testing. See also: https://nixos.wiki/wiki/Nixos-rebuild#Internals
+
 ## niv: Dependency management
 
 * https://nix.dev/tutorials/first-steps/towards-reproducibility-pinning-nixpkgs#dependency-management-with-niv
@@ -435,12 +435,18 @@ config.home-manager.users.yoda.programs.zsh.history.path
 #=> "/home/yoda/.local/share/.histfile"
 ```
 
+### Show Nix configuration
+
+* https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-show-config.html
+
+```shell
+nix --extra-experimental-features nix-command show-config
+```
+
 ### Evaluate NixOS configuration to JSON
 
 See also section "NixOS Configuration Debugging"!
 
-TODO: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-show-config.html
-
 * https://discourse.nixos.org/t/can-i-run-nix-instantiate-eval-strict-on-my-configuration-nix/7105/4
 
 This evaluates `configuration.nix` (single module):
@@ -455,7 +461,7 @@ import ./hosts/yodaTab/configuration.nix  {
 ' > evaluated-config.json
 ```
 
-Then open [evaluated-config.json](evaluated-config.json).
+Then open `evaluated-config.json`.
 
 ### References