Fix utility script bugs

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/installer/README.md

@@ -1 +1,13 @@
 # installer
+
+I have automated myself out of a job. How to use:
+
+1. Boot into installer
+2. Unlock luks partition
+3. Run the following commands:
+
+   ```
+   cd /etc/nixos
+   direnv allow
+   sudo ./lib/scripts/install.sh
+   ```