Add shell.nix file-template

modules/editor/file-templates/config.el

@@ -62,6 +62,7 @@ don't have a :trigger property in `+file-templates-alist'.")
     ;; Markdown
     (markdown-mode)
     ;; Nix
+    ("/shell\\.nix$" :trigger "__shell.nix")
     (nix-mode)
     ;; Org
     ("/README\\.org$"

modules/editor/file-templates/templates/nix-mode/__shell.nix

@@ -0,0 +1,9 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+with pkgs;
+
+mkShell {
+  buildInputs = [
+    ${0:`%`}
+  ];
+}