elixir_1_11: init at 1.11.0

Set elixir_1_11 as default elixir version.

pkgs/development/interpreters/elixir/1.11.nix

@@ -0,0 +1,9 @@
+{ mkDerivation }:
+
+# How to obtain `sha256`:
+# nix-prefetch-url --unpack https://github.com/elixir-lang/elixir/archive/v${version}.tar.gz
+mkDerivation {
+  version = "1.11.0";
+  sha256 = "0mxckjdy2gbmymvbi1bf146nhmz4icvq6917g8nbyi1gaz5l8rn2";
+  minimumOTPVersion = "21";
+}