ajout documentation sur l'utilisation

README.md

@@ -1,3 +1,23 @@
 # Custom NixOS Live CD
 
 After partitioning and mounting of your partitions under `/mnt`, go to `/iso/custom` and run `make`.
+
+## How to generate .iso from NixOS ?
+
+1. clone git repository
+
+```bash
+git clone --recursive ssh://git@gogs.prunetwork.fr:10022/nixos-config/nixos-livecd.git
+```
+
+1. run `make`
+
+```bash
+cd nixos-livecd
+make
+```
+
+1. use generated iso
+
+`nix-buil` tells you where it was generated
+