docs(install): stitch the README → template first-run handoff — item 6 complete

Slice (c), the last of the docs review: the install/first-run story
read end to end against the tree. Facts held (mkFlake args match the
table, disko's @snapshots + hibernation swapfile, .#default/.#me
naming); the one seam — README §3 never pointed the manual path at the
template README's first-run steps — got a connective paragraph. Item 6
deleted from BACKLOG; ROADMAP § Full docs review flipped to ✓.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -131,6 +131,12 @@ mkdir my-machine && cd my-machine
 nix flake init -t "git+https://git.bemagri.xyz/bernardo/nomarchy.git?ref=v1"
 ```
 
+The template's own README then walks the first-run steps: a real
+`hardware-configuration.nix`, `git init` (flakes only see tracked
+files), the two first rebuilds, and landing the checkout at
+`~/.nomarchy` so the theme CLI finds it. (The installer does all of
+this for you.)
+
 You own two files day-to-day: `system.nix` and `home.nix` (plus
 `theme-state.json`, written by the CLI). Your `flake.nix` is set up once —
 later by the installer — and never hand-edited; it's a single call: