Add shell.nix and .envrc for great good

Signed-off-by: Manuel Mendez <mmendez@equinix.com>

.envrc

@@ -0,0 +1 @@
+which nix &>/dev/null && use nix

shell.nix

@@ -0,0 +1,14 @@
+let _pkgs = import <nixpkgs> { };
+in { pkgs ? import (_pkgs.fetchFromGitHub {
+  owner = "NixOS";
+  repo = "nixpkgs";
+  #branch@date: nixpkgs-unstable@2020-11-04
+  rev = "dfea4e4951a3cee4d1807d8d4590189cf16f366b";
+  sha256 = "02j7f5l2p08144b2fb7pg6sbni5km5y72k3nk3i7irddx8j2s04i";
+}) { } }:
+
+with pkgs;
+
+mkShell {
+  buildInputs = [ go nodePackages.prettier shellcheck shfmt terraform ];
+}