Updated the Nix cache information in the README

Author: koslambrou

README.adoc

@@ -192,8 +192,9 @@ To set up the cache:
 . On non-NixOS, edit `/etc/nix/nix.conf` and add the following lines:
 +
 ----
-substituters        = https://hydra.iohk.io https://iohk.cachix.org https://cache.nixos.org/
-trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+substituters = https://hydra.iohk.io https://cache.nixos.org/
+trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+extra-experimental-features = nix-command flakes
 ----
 +
 [NOTE]
@@ -205,8 +206,8 @@ You must be a https://nixos.org/nix/manual/#ssec-multi-user[trusted user] to do
 +
 ----
 nix = {
-  binaryCaches          = [ "https://hydra.iohk.io" "https://iohk.cachix.org" ];
-  binaryCachePublicKeys = [ "hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=" "iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo=" ];
+  binaryCaches          = [ "https://hydra.iohk.io" "https://cache.iog.io" ];
+  binaryCachePublicKeys = [ "hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=" ];
 };
 ----