Update README

README.md

@@ -2,8 +2,7 @@
 
 Note:
 1. Comment out fetchTarball and mailserver for initial installation,
-   I don't know why but there're issues with fetchTarball when it runs
-   from live nixos installer.
+   because of [this bug](https://github.com/NixOS/nix/issues/2405).
 
 2. Some cloud providers disallow outbound SMTP by default. Check it if
    there'll be issues with outgoing emails.